I've searched and done some reading, not sure exactly what the most probable cause is... '97 GTP w 179k on (assuming) original trans. I haven't owned this car very long nor have I been able to drive it very far due to brakes/no registration yet. I realize this is a lot of miles for this trans, but I'd like to fix it for now if at all possible. Car has not been highway driven in a long time, supposedly transmission shifted fine last the car was driven.
Anyways the 1-2 shift and reverse feels nice and firm, right on the money. I dropped the pan (fluid was long overdue for a change -tan/brown, but did not smell burnt) changed the fluid/filter. No metal shavings at all in the pan and very little clutch material on the magnet.
Problem: Trans will "try" to go into 3rd under steady acceleration at roughly 3500rpms and will kind of "buck/jerk" at that time with some noise. It feels similar to a misfire but the car does the same thing under load or not. If I back off the throttle, it will fall right into gear. I haven't been able to drive it up to speed for fourth gear but it seems to upshift hard or late the same as going into 3rd with the front of the car jacked up (need to let off the gas for shift). I did not notice any slipping while in any gear when driving the car. Downshifts seem to be ok. I have not been able to hook up a scan tool and check for DTCs yet, will do asap.
I'm thinking I might try taking a look at the accumulator springs and installing a "shift kit". I recently installed a trans-go valvebody kit with a few other upgrades in a used 4L60 with great results...
Any help or insight would be greatly appreciated!
