Power Loss, need to get to 100% so I can sell it!!

Car: 1988 Pontiac Firebird Formula 350 (L98 5.7L Automatic), Mileage is almost 125k.

Problem: When the engine is warm and I floor the gas it feels and sounds like there's misfiring. There are intermittant power surges randomly while flooring it. When the engine is cold, everything is normal.

Symptoms: I removed the #1 spark plug and it had a light coat of oil on it (it was black). When the engine is cold, the transmission will start in second and shift to third around 15 mph, making for little normal acceleration and also when it does so it feels like letting out a clutch pedal slowly instead of the normal hard shift. The fan runs constantly and the A/C is off. No codes are being thrown.

What's been done to try to correct the problem: I replaced the oxygen sensor, all vacuum hoses, the intake manifold upper/lower gaskets (they were worn), and patched a leaking AIR system line. I set the timing to 1 degree advanced of the factory setting.

Guesses as to what it could be: Spark plugs and wires (next on my to do list), torque converter, or transmission fluid and filter need to be changed.

*Side note: What works fine when cold and can malfunction when warmed up?

What kind of oil pressure are you registering while its hot?Any lifter noise?

unhook your temp sensor,and note any idle changes.If the idle is less than 1500 RPM's,take it for a spin around the block with the temp sensor unplugged,and see if it clears it up.if so replace it.it sounds to me like your fuel mixture is off.did the plug smell like gas?You said it was covered with oil,but i suspect the black on the plugs,is due to a bad fuel mixture,instead of oil.
Also,go ahead and change the plugs and wires,before you deem your problem as engine mechanical.I think your problem is in the tuneup.Considering that your fan stays on all the time,im wanting to say the temp sensor needs replaced.Sombody has probably added a *aftermarket*wire to get the fan spinning wich can cause damage.What does the temp gauge say?could the engine be overheating?All the parts i have spoke of added up is about fifty bucks.

I have a question witch temp sensor? Air intake or another?

i was talking about the coolant temp sensor.he said the fan stays on all the time. the temp sensor tells the ecm to trn the fan on.it also tells the computer what mode to be in.another pain in the neck wiring job

Well I replaced the coolant temp sensor, no difference in the problem. But while I was at Autozone I won a raffle for a $10 gift card. I'm gonna buy the radiator fan switch with that, see if that helps the fan problem. I'm also going to do the spark plugs tomarrow, which I think is what's gonna fix it. But with my luck so far, nothing has fixed anything, so maybe not. I'll update tomarrow though.

i figure your engine mechanical is fine,because it runs okay in open loop mode(pre-set stored info)
but has a problem once it lets sensors take it over in closed loop mode.i just think it wierd that it doesnt throw any codes.Have you checked it with a true diagnostic system or did you flash code it?All your computer knows,is what the sensors tell it.its not abnormal to have some lying sensors,and the computer just believes its bullshit and moves on.Check all the wires on it.I have dealt with a lot of buicks with shorts in the ignition module wires.due to poor routing and the shielding of the wires all melting .before you throw much more money in sensors,check the wiring.I think sombody has added an extra wire to the fan to activate it.if the fan stays on all the time,it can cause problems with overcooling.

Well the only reason I don't think some1 jumpered a wire to the fan is i've had the car for 2 years and it just started this. I don't think it's mechanical either for the same reason as you...but I don't know sensors and engine performance stuff yet (next semester I learn), I know engine mechanical basics. If the spark plugs don't fix it, then i'll be completely lost...some people were saying TPS a while back (had the power loss for a while now).

Also it does throw a code, it's been throwing it on and off randomly since I bought the car, but it came back the other day. Code 36, burn-off at MAF sensor circuit. There was a bent prong on the MAF sensor plug, which I bent back...but i'm trying to eliminate everything else before the MAF because the MAF sensor costs $180 which I don't have for this car.

If it was a 80's cougar i would tell you its a converter.My friend has a cougar thats been thru 3 cat converters,and every time one goes out on it, it makes it sort of rock back and forth under acceleration,and miss at idle.also it gets a major power loss.does yours not have a oil pressure gauge?

its throwing a maf code?does it show the code when it hot or cold?or just random?

Well as far as the converter goes, I welded it on, could that ruin it?

The code comes on randomly, and only right after the car has been started, never comes on during driving or anything.

I have an oil pressure gauge, and it stays between 35 and 15 usually. I know that's a big range, the oil level is normal, and the oil itself is brand new (50 miles on it, 10W-30). Where should it be?

Welding the converter on shouldn't have hurt it as it gets plenty hot on its own and welding them on is the proper way to do it so long as it was done correctly. How many miles are on that engine (is the 125K on the engine or car)? Does running a higher viscocity oil bring up the pressure? Say 20w50?

125k original engine, and i've never tried a more viscous oil.

15 psi of oil pressure is not enough oil pressure to work the lifters.it has bad cam bearings or somthing.i bet thats what the problem is.I just dealt with a 454 that horton rebuilt,and it would hammer out after it got hot.i sent my customer back to horton ,and they rebuilt it again.You may need an oil pump,but if it runs okay while its cold,and bad while its hot,and the oil pressure is 30-15,the cam bearings are shot(if it dont knock)

Well it's not that it runs bad when it's warm, it just misfires until I get into higher RPM. It idles fine, and pretty much everything is fine up until flooring it, then it misfires...didnt have time to do the spark plugs the other day since i'm dropping the tranny on my other car, but can temperature affect spark plug performance at all?

yes.temperature makes a big difference.the difference between r45ts,and r43ts,is the temperature rating.

I have no idea what those are lol. Could you explain?

those are spark plugs.

well, thats what i figured, but i thought maybe there was more of an in depth explaination lol.