I've got a 5.0L TBI engine from an 88 Camaro that I'm having a problem getting it to idle down(1200 for a manual tranny).

It is almost completely stock. The only things that are not stock are the injector spacer, throttle body spacer, and the throttle body itself(it is one of the Turbo City specials)

Since swapping on the Turbo City throttle body and an attempt to use a Painless wiring harness, it will not idle. I have since replaced the Painless junk with a factory 88 harness. I have also tried a factory throttle body. All the sensors are new(TPS, IAC, o2, iac, water, air cleaner temp, distrib module)

The only things I haven't replaced are the actual distributor and ECM.

I've checked for vacumn leaks to no avail. I've tried setting the TPS, IAC, and timing per the factory manual.

I'm running out of things to check and it has become a smog issue at this point.

The one thing that has crossed my mind is that the ECM I'm using is for an automatic while I'm using a manual tranny. Can I simply swap a manual prom into my ECM to "fix" this?

Lastly, what am I supposed to do with the park/neutral switch with a manual tranny? Should I hook it up based on the parking brake?

TIA,
John