I just bought a 93 Dodge b250 conversion van and it seems to be losing power and spitting when i intially start it but after about 5-10 minutes it starts working just fine till i try to bring it to a constant speed at 65 and then it will jerk slightly and i ll have to change speed to make it stop doign that i am also seems to be losing oil pressure when the oil seems to be the at the full level.

 

This problem plagued my van until the motor finally went. It seems that the oil pickup is prone to sludge and gets clogged. Drop your oil pan and
clean everthing especially the tube, Good Luck!

Brian