I have an 89 ranger 2.3 dual plug, 5 spd. I changed the engine in it to a 92 ranger 2.3. It ran great, had tons of power and then all of a sudden it starts bucking and jerking after start up (Revs up and then goes to low idle till it picks up and acts normal, also sometimes quits). It also bucks and jerks during acceleration, sometimes (Usually during higher throttle). I replaced the fuel filter, fuel pressure regulator, check the coil packs, vacuum lines, and seems like just about everything.

Any ideas? I'm at a lose guys. Need some help.

Thanks in advance,
Stephen