The first thing you should try is to change the transmission fluid. Only problem here is that you can't get it all out because there will still be some in the torque convertor.
If however the problem seams better after changing the fluid then after a good long run and when hot change the fluid again.
It is worth noting that slip can occur from lack of fluid and not to much. This would indicate to valves being contaminated with old fluid. So a good change of fluid may just cure the problem.
chris, December 2005
