My 1984 automatic 2wd started acting funny in the last few weeks. When I first start it up and it is cold it won't go into gear (forward or reverse) until it is revved up high enough. Basically you put you put on the gas an nothing happens and then all of the sudden it catches and you are flying backwards. This is dangerous when trying to get out of a parallel parking spot. Also when I come to red lights and I'm sitting there for about 30 seconds it lurches forward all of the sudden. My ATF is topped off and so is the brake fluid. It has started to get colder in the last couple weeks, but only around 50 degrees F. The problem seems to stop once the van is warmed up. Any ideas?