My 302 has a very rough idle in reverse and drive only… when I park it sounds fine… The idle is also very rough when the car is wet or when its raining…any ideas why? Its so rough of an idle the car jerks around…
probably spark plug wires. under a load they are arcing to an outside piece of metal like the block or valve covers. just idling the cylinders dont have enough resistance to firing to cause a serious arc. could also be distributor cap. find a dark spot on a misty night and open the hood with someone putting it in drive while holding the brake on. someplace there should be some interesting electrical arcs. or just do a plug wire and dist cap replacement. should cure it.
Might be a vacuum leak. You don't say whether the engine is stock or modified - a lopy cam can cause problems. A bad EGR valve or PCV valve can do the same. PaulS
its a stock engine with a new dist cap and plugs with fairly new wires... I also have oil coming out of the front of the motor where the distributor is... Could it be faulty wiring?
Vacuum leak. Idle the car and take some carb cleaner or something around all the possible places for a leak, listening for changes in idle speed.
