I have a 2005 Suburban, it has a random misfire code, that comes and goes.
It had the 5.3 flex fuel motor. The motor checked out very good but was down on power. A couple different shops could not correct the problem.
It was missing on 1 and either 2 or 3.
Replaced all the injectors, plugs and the coils on the misfiring cylinders .
The next move I replaced the engine with one out of a pickup, none flexfuel. I transferred everything over with the replacement engine. Coils, Injectors and everything associated.
I then had another shop go over it again checking all the grounds.
It still has the misfiring.
I am down to replacing the computer.

Can anyone give me any suggestions on how to fix the problem?