Engine Performance problem
1989 Ford Bronco 6 cyl Four Wheel Drive Manual 149000 miles
4.9 ltr, NEW MAP sensor but have to unplug to get engine to run half way smooth. No error codes when hooked up to analyzer. Throttle position and most other sensor's replaced. Main computer swapped out with no change, also ICM. What else could it be?
I did not see where you have checked/adjusted the timing. This is the first step towards driveability problems when possible.
Next try cleaning the mass air flow (maF) sensor on the throttle body.
These also have a common problem of the IAC Idle air control sticking/wearing out. You mentioned that most of the other sensors were replaced but not specifically so I am adding this just in case. Most commonly it just causing poor idling and stalling at idle problems. Tap the top of the sensor with a screwdriver handle and see if it smooths out. Replace as needed.
Please post any follup questions or if none of these pan out we have many more ideas.