just bought 1989 iroc 350cid w/700 r4. car ran fine for first 20 min then engine began revving while on the highway doing 55mph. pulled over to the side, car stopped shifting properly. while shifting through the gears, engine idle changes, but car remains in park - will not roll in any gear. is this a tranny problem? someone suggestes valve body as possible culprit.

 

What gear's did it begin revving at 55mph? My 700r4 Had that problem in 3rd gear, except that it appeared to be in more serious shape. I took it to a tranny shop, he said it was all caused by my kickdown cable being a little longer then it should be, so she got rebult lol.