99 Grand Am off and on Engine Problem

I have a 99 Grand AM SE. I have been having a problem lately that is getting progressively worse. At first very infrequently the service engine soon light would blink and the trac off light would come on. At the same time I lose alot of power as if I'm running on two cylinders. Now this is about half of the time and getting worse. Does anyone have any ideas?

get the computer error codes read by an OBD reader.

problem is most likely the fuel system

I have the same problem w/ my 99 Grand AM. I replaced injectors, coil packs, coil tower, temp sensor and battery. Car starts and run fines, but on occasion it will start to idle very rough, but won't die. I am starting to get an Error Code 0420. I don't think this is the cause for the rough idle. Does anyone have suggestions? I have put over $600 in repairs, trying to fix the problem but it won't go away. Can the Catylitic Converter cause the engine to idle rough for short periods of time?

I have a 99 Grand AM SE. I have been having a problem lately that is getting progressively worse. At first very infrequently the service engine soon light would blink and the trac off light would come on. At the same time I lose alot of power as if I'm running on two cylinders. Now this is about half of the time and getting worse. Does anyone have any ideas?

I have the same car, 1999 GA SE, I do my own work, last month pulled the transmission out of the car for an overhaul, got by with it for $850.00.

I'm also the one that posted the thread on Prolong WARNING!!!

This past tues. 11/28 had to pull the pan off to clean out the pump and sludge from Prolong.

Last July did an intake manifold gasket on it to fix a coolant leak. Do all my own oil changes and break jobs, tune ups, etc.

When it comes to this sort of thing!!

TAKE IT TO THE DEALER, Have them run diagnostics on it, and tell you what is wrong.

Last spring my 99 wouldn't start one morning, I replaced the ignition module for $109.00, no go, replaced the crank trigger $40.00, no go. Towed it up to the dealer, paid $65.00 diagnostic fee, they told me it was the crankshaft sensor, I replaced it for $35.00, in the parking lot at the dealer. Spent $150.00 on nothing, if I had taken it to them in the first place it would have only cost me $100.00. As was spent $250.00 on the car!!!!

When it comes to the electronics on the car, let a Pontiac dealer check it out, they are trained on the car, they see all kinds of problems that you have never seen, and in the long run it MIGHT save you some money. You can always have the work done elsewhere!!! After they do the diagnostics!!!!!!!!!!!!!!!