I have a 1993 c1500 stepside with a 4.3L and swapping it with a donor engine 5.0L that came out of a 1990. We have rebuilt the engine before proceeding with the swap.

I have read that when it comes to TBI it is a easy swap, as their's little changes that needs to be done.

I have swap the PROM of the v8 engine into the 1993 computer, but the check engine light started flickering when switching on. Then i just replaced the complete ECM and the engine starts fine, but after a few moments of idling the engine shots down. With the V6 ECM the engine will idle without shutting down, what could be causing this? Note: i have the v6 throttle body installed, as i don't have the gasket yet to replace the injectors (old throttle body, the throttle position sensor has changed from 90 to 93, that's the reason using the v6 throttle body).

What could be the causing this or what did i miss?

What have been done:

• Engine mount was replaced with the V8 engine mount.
• Fuel line needed to be changed, as they were short.
• Replaced the complete exhaust system with that came off the 1990 c1500 (headers).
• Replaced the temperature sensor to match the wire plug.