Ok..ive got a 1995 pontiac bonneville, the problem is that every so often it simply wont start..I replaced the engine awhile back and the engine it has in it now has around 30,000 miles on it, but sometimes ill go to turn the car on and it will turn over fine but doesnt start..just keeps turning over...sometimes it would do it and start after 5 minutes..sometimes (more recently) it will just sit there and not start for an hour.. but usually after around 30 min it starts.. Ive taken it to the mechanic (thats where it is now) its been in there 5 times, twice with a different mechanic and 3 times with the one it is now..The mechanic says its the ignition sending unit or something like that , and he replaced that , got the car back..still does the start thing..so he changes the plugs and wires and puts another ignition sending unit in it ,and it still does the same thing..i dont know much about cars..but ive paid around $1,200.00 on this mechanic alone so far trying to get it fixed and its still not fixed..so i figured id post here because im sure someone out there has had a similar problem?..so any help would be greatly appreciated .

ICM??

Okay... Has he changed the Coils?

Crank sensor may be on the way out. I had the same problem and there'* a few posts on this subject. I would have to wait 5 minutes to start the car AFTER I had already been driving (engine hot). A few times I had to wait a while.

Do some search on "crank and sensor" and you will get some feedback.