Try cleaning the throttleplate with choke cleaner on both sides as well as the iac hole. It may be sticking. If that doesn't cure it then take to a trans guy so he can scan for codes as alot of times those don't show on the auto part scanners.
If the problem is electrical, there would usually have trouble codes and since none is present, it would be mechanical or hydraulically related.
Slipping can be due pressure leaks in the system.
It could be a failing seal, which explains the intermittent condition.
You would need to perform pressure test to check if anything is wrong.
Thursday, March 29th, 2012 AT 1:16 PM