I've read all the above... converting to carburetor isn't really a solution and will make your truck worse.

I noticed that unless you failed to mention it, you didn't check the single most common cause of rich running, the coolant temperature sensor. Not the one for the dash gauge, but the one for the EFI system - this is where Bosch-type EFI systems get their baseline fueling from. If the computer sees that the sensor is reading as if it were cold outside, it will enrich the mixture accordingly. This is given priority or more importance than the intake air temperature sensing in the MAF. Check that, check the connections between it and the computer and you will probably find your problem.