My girlfriend's '98 2200 has had a problem for the past year where it will misfire while the A/C is on and you are maintaining a constant speed between 45-60mph. It doesn't misfire outside of that. I'm guessing it is the fuel pump. Anyone have any ideas?

How long has it been since these [arts have been changed?.

spark plugs / fuel filter / wires / fuel injectors serviced.

I've changed the plugs, wires, and fuel filter. Never serviced the injectors. I did poor some lucas fuel injector cleaner in for a couple tanks, but that stuff isn't very effective compared to a professional cleaning.

On the '93/'94 earlier Cav alternator there is a dedicated Brown/White wire running directly from the alternator, which, when the engine is running feeds the 25Amp A/C /Heater fuse.

Just a thought that it may be an electrical fault in this wire or the alternator, only showing when the A/C is ON.

You may not have this wiring in the later Cav's.

Alont