92 rs car will not start or run with prom installed will run without prom however not correctly. gm says prom is bad however i have two ecms and proms and they both work in another car. any ideas can you help?

 

That just about takes it right down to the ECM connector wiring and beyond. If a replacement ECM and PROM thjat works in a different vehicle doesn't work in your's you need to look outside the ECM - possibly right outside.

On the other hand, if the "test car" is a different model/year, there may be some differences.