Hey there folks, I'm in need of some help. I posted about this before but in the general TBI thread. Hoping someone here can help.

First off the car. 92 Camaro RS 305 TBI 5 speed car. In theory all factory except that which "bubba" has tinkered with. And that's part of the question here.

Secondly the problem(s). Upon first buying the car it ran fine, idled smooth etc. Well it eventually started running strange. While driving down the highway you could feel the power come and go, especially while trying to accelerate. Well while trying to chase down the gremlin and doing a full tune up and checking all the sensors I decided to poke at the ECM. When I pulled it out it looked wrong. With help from another forum member I realized it was not the proper ECM. It was a 8062 from a truck instead of the 8746 it should have. Well I sourced a replacement, 2 at this point actually. When I hook up the 8746 the car goes crazy. First off it's super hard to star . Then you have to flutter the gas pedal to keep it going. After doing that a couple minutes i can let off and it will idle, very roughly. On top of that, both of the 8746 ECMs throw a code 42 and 44. Both ECMs run like this. So i expect they're good.

Thirdly (Grammar?) My only current theory which I have yet to check is could whover did this, repinned the wiring Harness to make the 8062 ECM work and that's why the correct computer wont work right? I'm open to suggestions and I have a scan cable so I can datalog if that's helpfu .

Lastly, why would someone swap to a 8062 ECM? Is there a legit reason?

Thanks in advance!