I have a 5.7TPI IROC with auto and 64,000 miles. A new quirk has developed that I would like some help on. When traveling in high gear (OD or D3, happens in both) when not on the gas, the rpms drop about 300 to 500 and then jump back up. Almost feels like it is gpoing out of gear and then back into gear. My mechanic is not sure. He added some kind of stuff to the fluid and said drive for a while and see if this helps. He also thinks it is because of the 2.77 gears in the rear and the overdrive keeping the rpms at cruizing speed so low that it locking up and unlocking (my words not his, that's what it sounded like he said). Any words of wisdom out there?

 

When you lift off the gas the torque converter unlocks, thus free wheeling the motor. Sounds normal. As for the gears, they're factory, thus they're not causing a problem.