1994 transmission issue. About 3 weeks ago my transmission was taken out to replace the main seal (oil leak) and when I got it back it started having transmission issues. Two things have happened. First, When I go about 5 mph in reverse it pops into neutral. Second, when I put it into "D" the rpm's go up without it moving. Eventually, the transmission engages and goes. I took it back to the mechanic and had the transmission fluid changed. No change. I took it back a third time and mechanic drove and said transmission is fine. Unfortunately, the problem persists. Thank you for any help!