I did post a while back in the truck section with some good info but still having issues.

1989 W250 360 pretty much a unmolested original truck. What would the cold weather affect on start up? Been struggling trying to figure out what causes it to run sorta rough spit and pops back through the throttle body and speed up and slow down at idle. I put it in the shop at 65 degrees and it runs perfect, put it outside in the 20 degree weather for a couple hrs. and runs like crap again. Sick of throwing parts at it.

New map sensor, throttle positioning sensor, ignition temp sensor,02 sensor,hall effect pickup in the distributer, different ecm. Hot air setup from the exhaust manifold appears to be working. Also took the idle speed motor off and it still speeds up and slows down, back on there now. I checked the codes and it only shows the battery disconnected code. I plugged the line to the vacuum booster with no change. Timing was spot on. What am I missing here? I am at a loss