Ok so I have the 86 firebird and the 2.8L in it is not running right. It will start up and rev really good and sound nice and strong but as soon as you put a load on it or put it in gear and try to drive I have no power at all and it sounds like the engine is struggling. Pep boys (who are pretty much worthless and I have discovered the people there know less about cars than I do..THEY ARE IN NO WAY SHAPE OR FORM MECHANICS...they just know how to read a machine and thats it) but anyways they said that it could be the mass air flow sensor and the O2 sensor or the timing. Well I had them try to time it (they couldn't) and it didnt work. So I took it back home and I replaced both the sensors myself and unfortunately the starter went out so I went ahead and replaced that. Now it is running a little better but still is having the same issues. So I dont know what else it could be? I guess I need to take it and have it re-timed somewhere because I also tried to time it with my dad and everything seemed like it was right but now its still doing the same thing. So any suggestions on what it could be? Any input would be appreciated. Thanks everyone.

Did they give you any codes to go buy? In other words, if you plug in a code reader (or jumper the ALDL) does the computer give you any codes to help diagnose?

Also, when was last tune-up done (Search for TomP's Tune-up thread).

The only code that they said was showing up was the mass air flow sensor and like I said I already replaced that. And the motor has almost been completely rebuilt, new water pump, alternator, oil pan, starter, rotor cap, wires, battery, spark plugs and wires, new vacuum intake hoses..just about everything really and I just changed the oil and added more antifreeze...I'm thinking the cat may be collapsed which would explain the loss of power so I guess I might try and get the cat cut out and straight pipe it to the muffler..and if that doesnt work since pepboys cant do anything for me I guess I'll have to take it to Chevrolet and see if they can figure it out. I really cant think of anything else it could be so I just dont know what to do.

Sounds like your cat is clogged. If you dont mind having a loud car for a lil bit. Try removing the cat and then go drive it...or just replace it with a high flow one like magnaflow, im sure the cat on there is pretty old if not original anyway.

Yeah thats what I am thinking too. I just had my dad go outside and rev it up and I put my hand behind the exhaust pipe and sure enough it was shooting out little shards so I'm going to go get the cat cut out tomorrow and see what happens...And no I don't mind the noise, I used to have a 98 Firebird with the 3.8L V6 in it with a flowmaster crossflow exhaust and I had the cat go out in it so I had it cut off and it sounded fine to me.

Well I had the cat cut off and that didnt fix it so I had the muffler replaced and its still doing the same thing...I tested the distributor by taking the spark plug wires and spark plugs out of each cylinder and they all had spark but the third cylinder spark plug was black and was slightly wet. I guess it could be a fuel injector? Im not sure but I'm tired of guessing and checking so I took it to chevrolet and dropped it off and they assured me that they would pin point what is wrong with the car and it wouldn't be a waste of my money. So they said it will be ready tomorrow or Monday so I'll let you know what it ended up being when I find out. Thanks again for the input though.

A wet black plug is a sign of an oil control problem, be it rings, valves, or even a valve cover gasket. When you go to replace the plug, step up to an R43TS or whatever the next heat range up from your current plug is (if you're not running AC Delco plugs). The new plug should help burn off the oil a little better and last a little longer before fouling.