I just got a 93 Jimmy, RWD, 253k miles. Guy told me the previous owner was complaining about the transmission not operating after a long drive. He replaced the filter and fluid and didn't have any issues. I took it on the highway today, testing it out. In overdrive, i pressed the pedal to the floor and heard a loud pop and the engine sounded like it was in neutral. I let off and accelerate normally and it moves down the road. When I come to a stop or slow down to where I think I should be in a lower gear the transmission acts like it's in neutral again. This happens in overdrive and drive. I can start off in 1st and shift through the gears all the way into overdrive. If I accelerate hard in overdrive though it won't down shift just start revving like it's in neutral. What could the pop have been? I don't think it's a clutch pack issue because i can move in all the gears once I'm in the proper gear range.
