So...I bought a 1992 Chevy k1500 with an L98 block and 1188113 aluminum heads, factory throttle body, Edelbrock 3704 Performer intake, shorty headers with free flowing 3in exhaust, Comp Cams Dual Energy 203/212 Hydraulic Flat Cam, a 1227747 86ASDU ECM with a Hypertech 120222 PROM, and no idea where to start with the tuning aspects. I bought the truck like this and wasn't expecting everything in the ECM department to be wrong. Injectors spray patterns are uniform and doesn't seem to be having any fuel delivery issues, and I always run 91 octane or better gas. I've already checked and cleaned my grounds. It barely idles above 500 when warm, and surges when I stop. With the timing advance unplugged, it will idle all day long at 0° tdc with no movement, but as soon as it's reconnected, and I advance my timing light to bring the line back to the 0° mark, it's jumping all over the place to about an 8-10° range before and after tdc. I pulled a code 42 (Electronic Spark Timing) but it's a brand new distributor, module, and coil, that I tested and are all working like they should. All sensors and fuses are brand new and functional. So this has led me to believe either the ECM is bad, or it's just delivering the wrong information. I assume it's because of all of the aftermarket parts (especially the cam) combined with a stock tune. I'm way out of my league when it comes to the electronics, but I can and have replaced almost every moving mechanical part in this entire truck so far. Any and all input would be greatly appreciated.
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