ac compressor and fan will not come on. its on a 94 olds cutlass fuse is good ,relays are good . i can run a jumper wire where the relays plug in then they will work.

1994 Chevy 2500 PU, 5.7 L, auto, 180000 miles intermittent problem-now consistent, runs like it has plugged fuel filter or timing is off. Changed air filter, fuel filter, cap & rotor, plugs. I have used fuel injector cleaner several times...no improvement. Changing the plugs, cap & rotor improved it's "perkiness", but the roughness persists. It first presented itself entering the intererstate...choke, cough and almost die four times within 1 mile, then later it would do it climbing a mountain but still not consistently, until lately, now it runs rough most of the time. Vacuum leak? Where? It is using some oil now...catalytic converter? Help. Thanks