My 1995 2500 4x4 listed below was working great. I brought it to a mechanic to change out some brake lines and get inspected. Master cylinder, wheel cylinders, calipers and some other misc parts I get the truck back and the converter is not locking in overdrive off. In overdrive on you can get it to go but I have to play with the pedal a bit and it wont stay locked. Any Ideas? TPS? if so where is it, where can I get it and how hard is it to change. Thanks