first of all, this is the best forum. ive been on other forums an have been on forums for my RC racing and everybody on here has been such a big help an very friendly. love it. heres the deal, i dont know a thing about trannys, let alone automatics, which is what is in my d50. when i was putting in new motor, i had a mechanic put in new filter kit an gaskets in my tranny heres the problem. every once in awhile when its in drive and starting from a dead stop, it feels like it is slipping real bad. my truck will move, barely, but its like its in neutral almost, then it will catch an start to go. an it seems like it only does it when its cold. also, it wont do it if i shift it manually. it never did this before my new motor an having tranny serviced. any ideas guys?