I've had my 82 C3 for about 4 years. It sat in a field next to a pond in New England for 3 years. I drained the old gas. put in new gas and had some brake work done. It was and now is a good driver. After about a year, the idle went fast (1200 rpm) and the engine started surging during the first 5 mins after starting (cold). I shipped the car to Arizona and the car would barely stay running.
Took it to a local, he replaced the intake manifold gasket and was able to get it to pass the emission test here in AZ. I still had the high idle and surging. I replaced the chassis fuel filter. No change. I then replaced the fuel pump and the strainer/filter (in tank) That fixed the sluggish and most of the surging problem.
Before I left MA I had the AC serviced. It worked well there. Not Hot but removed the water out of the air. Once here in AZ the AC just barely got cool. Lots of 105-109` days out here. I found that the system was over serviced. I reduced the pressure in the system and recharged up to 55 psi. That stopped the compressor for short cycling causing the surges. So until the next "thing" I'm a happy camper. Normal idle, acceleration and AC operation.
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Nobody ever waves when I'm driving the Explorer.
K Woody