1994 Ford Ranger Violent "jerk" when accelerating

Prob: When driving usually accelerating, my truck will jerk very hard for a split second. Sometimes will stall, most of the time it won't. Also has jerked and stalled on me while on the freeway doing 65 mph. I coasted turned off all accessories and after 3 or 4 trys got it cranked up again. The jerking is very random and really scares the crapp out of you cause you never know when to expect it.

History: Prob statred with check engine light. Would idle rough when AC kicks on, voltage drops and wants to stall. When AC kicks off, idle goes up and runs fine. Took it into my mechanic. Gave 2 codes EGR bakcflow (hoses were missing, so I replaced) the EGR vacuum was tested and good. And coil pack code (replaced and the engine light still came on, made no difference. So I returned the coil packs and put back on originals) Engine light still on. Mechanic was puzzled. Then said it has to be ignition module, replaced and the engine light went off and drove fine, but occasionaly has the AC idle prob and the jerking thing. Replaced to the ignition module for another, still doing above mentioned probs. Got a 3rd ignition module this time a Motorcraft brand. Still doing the AC idle and jerking thing. He said put on the original ignition module. I did and the jerking thing goes away, but engine light comes on and the truck runs like crap. Put motorcraft module back on. He tested the fuel pressure and he said it was fine. The last thing he suggested is switching the exhaust coil pack with the intake coil pack. He is trying to save me money by not buying parts I dont need. Other than the AC idle prob and the jerking thing, the idle is smooth and the engine has great accelerating power, runs very well, best it ever has, accept the darn AC idle prob and the jerking prob. Any suggestions?