97 grand am cuts out on exceleration

need to know what is happening is it computer or sensor or what? 97 Grand Am 3100 V6 engine automatic trans had locked up motor. Mechanic installed a 97 lumina engine 3100 v6. Said it would work like a champ. When first started engine wouldn't run. Changed out ECM.
When I picked up car it would idol fine but when in gear it would only go about 20 mph then cuts out. Took back put another ECM in now it runs better but apon exceleration it goes and then bogs then picks up and then bogs over and over. you can put it in neutral and floor the cxcelerator and it seem like there is a govener. check engine light, battery light and theft light is on and shift indecator lights flash on and off. thanks for any help you can offer.

Hhmmmmmmmm. Boy, that's kinda tough, I do suggest you visit the chevy area, ask around there for info, since it a Chevy engine it has some
differences in wiring and sensor signals.

thanks . for the heads up .Maybe somebody out there will know what to look for and what to do to get this nice car back in good running condition