Ok, first of all, I am in no way an ASE mechanic. I'm in the learning phase, so please don't flame if this is a dumb question. I have an 89 Firebird w/a 5.0 TBI. When I used to be able to drive it, it would surge like it had more power, then the check engine light came on, and the car had no power whatsoever. It felt like I'm was suddenly driving a four-banger. The only way to get it to run normal again is to turn it off, and turn the car back on again. There is also a smell like something is burning when you stop to turn it off/on. I acquired the code, and it was code 43 (Electronic Spark Control) So a friend at work said it was an ignition problem, so I replaced the ignition module/coil. Now, my car will start, and idle, but when the rpm's drop below 1000 as the engine warms up, it will eventually stumble and die. If you keep your foot on the gas, it will run, but as soon as you let off, it dies. So I went and bought the haynes manual, and it says that the cause of code is either a defective knock sensor, or a defective ESC module. Also, under the trouble shooting section for the ESC, it says that "...loss of ESC signal to the ECM will constantly retard EST. This will result in sluggish performance, and cause the ECM to set a Code 43." Would a defective ESC module, or a knock sensor cause this? Am I even on the right track? I would just go out and buy both new parts, but I already spent over $100 on the ignition parts, and I don't want to waste any more money on parts that don't need to be replaced. Any help would be greatly appreciated.
Thanks

 

I should clarify, the car will run if I keep my foot on the gas. I have to drive it like a manual. I have checked for vacuum leaks, replaced the ignition module and coil, changed the fuel filter, put in new spark plugs and wires, and a new cap and rotor. I cleaned the IAC. I tried unplugging the IAC, and the car ran, although it idled around 1500 rpm, so I bought a new IAC, but the problem is still after I installed the new one. Anyone have any suggestions as to what to check/try?

 

Id start with timing

 

I finally had time to check the timing. I was shocked to find that it was around half an inch past the timing teeth on the retarded side! So I set it to 0*, and now it runs a thousand times better. I can't comprehend why anyone would set the timing that far retarded. But, I don't think the previous owner was very intelligent, because he installed one of the headlights upside down. Thanks for the suggestion Bird1994!