OK, so I have an 03 mazda protege, 2.0, appox 76,000 miles. My issue started about 1-2 months ago, I was on the interstate and had been going along approx 70 - 75 mph just fine, then suddenly the rpm's shoot up.. so i immediately let off the accelerator to get the rpms back down.. when this is happening mph is also dropping, and i couldn't keep it up, definitely wasn't able to go 70 - 75, if i tried the rpm would shoot back up, but no increase in speed. So I parked, we ended up having it towed back, got back, oddly enough started working OK. Couple of weeks later, started to notice rough idling, hard start, couple of tries, and it idled around 1500 - 2000 rpm or so.. check engine light came on, took to autozone, cylinder misfire, but then went away, works fine.. Was working good was on the interstate last week, going about 70, same situation happened as above, rpm shot up, couldn't hold high speeds. We ended up driving it back going like 55 mph, I've been driving around some around town going 45 - 55, but what happens is it takes off really slow, the rpm and the mph, I had a dump truck pass me at a dead stop as I tried to get it up to 55.. if I try to push to much the rpm will jump up, or if I hit a steep hill and try to hold the current speed. Someone told me it sounds like the transmission, slipping maybe, I'm not so sure.. would it do it then get better, and maybe the cylinder misfire isn't related to the current issue, I've heard it could be the fuel filter, or the plug and wires, plugs are clean though, I dont know.. any advice would be great.. If there is already a similar post, let me know, I looked but couldn't really find one..

Sure sounds like it's slipping. You didn't say if this is an automatic or standard shift.

If standard that's consistent with a worn out clutch.

If an auto it's got serious problems - start with checking that fluid level is proper,

T
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Tom Greenleaf - MetroWest, Boston
http://acsource.net/acforum/index.php

Sorry, it is an auto, with slap shift, that I rarely use until now, reason being when accelerating, very slowly, and the RPM's get up to like 3000 or so, I can just manually put it in the next gear, drops the rpm, but acceleration doesn't improve any, still slow.. it will change to the higher gear automatically, but since its acceleration is so slow, I try to help it along, I don't think its hurting or helping anything though.. I've been reading, is it any chance this could be starving for fuel, like a fuel filter, fuel pump, or fuel relay issue, or sounds more like a transmission problem?

Engine management problems can cause automatic transmissions to react adversely. Any drivablility concerns should be addressed, first. Do you still have a check engine light on? This is a real reach, but if you have had a misfire for very long, it can damage the catalytic converter. If the cat becomes plugged, this of course will cause an exhaust restriction. As in, reving the engine, but not going anywhere. I've seen them so plugged, that 20mph at full throttle was max. And, this can come and go with temperature. Sometimes, they will break up internally and a chunk of the cat will temporarily block off the pipe causing a severe loss of power. Turn the engine off, the chunk will fall back, and everything is good in the world. For a while. Sooooooo...Have the misfire rechecked. If everything checks out there, see a trans. shop.
Loren
SW Washington

No the check engine light is off, i went off after I had them run it at autozone just to see what was up.. A separate issue I didn't think was related but may be is this car sucks up oil.. really bad.. constantly putting it in, we thinks the valve guides are leaking as it smokes at start up, I'm soon to try to replace these, but at this point I consider it secondary as with the current issue drivability is poor.. could any oil leakage cause issues with the catalyst, leading to this issue? Or possibly cause issues with the ERG or the mass air flow, if so would that even relate to this issue? Sorry I've been reading alot, so trying to pull all my info in..

If it's burning oil, that is going through the cat, as well. Being a '93, the computer doesn't have the capability of misfire detected. I should have caught that in the first post. So, if AutoZone scanned it, it wouldn't have given them an answer to whether or not it had been misfiring. <sigh>. I'd recommend that you spend the money and have a shop check this out and get to the bottom of it. A backpressure test for the cat is quite simple. The rest will have to be done with a scanner/scope/gas analyzer, ect.
Loren
SW Washington

Its an 2003 model, but still same issue with the computer capability of misfire detection?

And, I even had my glasses on! An '03 does have misfire detection. Sorry, A-Z.
Loren
SW Washington

So today still running like hell, but the check engine light came on: Codes P0300, BBRandom cylinder misfire detected and P0172, BBRich Air/Fuel ratio bank 1.

Probable causes for P0300:
BB1- Lean air/fuel ratio
BB2- Weak ignition system
BB3- Engine mechanical condition
BB4- Vacuum leak affecting one cylinder

Probable causes for P0172:
BB1- High fuel pressure
BB2- Leaking injector or pressure regulator
BB3- Dirty/defective MAF sensor
BB4- Stuck open ERG valve
BB5- Engine Mechanical condition

I am at a loss..

Cardone Reman / Mass Air Flow Sensor Part Number: 74-10084 The MAF is in the rubber hose that goes from the air filter box to the plenum. You can take this out and carefully clean it. Spray electrical parts cleaner is probably the safest to use. This, to me, doesn't match your symptoms, but worth a try. The EGR valve, if stuck open, would be like a large vacuum leak. The O2 codes are probably a result of, not the cause, of your problem. Price: $177.99
Core*Corevalue is the used part that manufacturers use for rebuilding. AutoZone charges the core value to customers because manufacturers include it in their prices. When you return your core to AutoZone, we'll refund your core charge.: $45.00
Total: $222.99 Warranty:
1 YR

Loren
SW Washington