Erratic Idle 93 Grand Am

for the last year, I've had an Erratic Idle problem on my 93 Grand AmSE w/ V-6 engine I've had 3 different mechanics look at it. They've check vaccum hoses, Idle Valves, they've reset the Idle. No one can figure this one out. It only does it every now and then and only when the car is in Park position. Anyone have this problem and remedy
Thanks
Ronnie

How many miles? How recently has the air and fuel filter been replaced?

Well the 3300 will always have a slightly erratic Idle. First I would check a few little things, look in your fuse box and make sure the ERLS fuse is still good, then check your spark plug wires and replace any that are bad. If it still idles bad, then you most likely have a broken Park/Nuetral switch which basically means the car doesn't know whether it is in gear or in Park or nuetral so therefore the computer gets confused and messes upt he idle. Very common problem with the 3-speed. Should be about a $40 part, you can do it yourself or if you don't have time, take it to a shop and it should'nt take more than an hour of labor :)