1996 Ford Ranger runs rough when warmed up

1996 Ford Ranger mileage 133,000. The truck starts and idles well. However when it gets warmed up (probably a twenty minute drive) bucks jumps lurches almost acts like it is shutting off and on. This started happening after I had tune up (in July ran very well until Nov.) New dist, wires, plugs, coil, fuel injectors cleaned. Started just an occasional jerk then got so you did not dare drive it far. One garage said needs new throttle control valve, installed did not fix, next time EGR valve and PVC valve, installed still no fix. Next time they retarded timing ran well for maybe two weeks, no power but didn’t jerk. Now they are suggesting idle control motor? Another said the fuel pump. Any suggestions before I donate it to charity? I don't mind spending the money to fix it but when it doesn’t fix it I get frustrated. Should I take it to a Ford garage? Please help!