I feel your pain,I have a very simluar situation;I had a C4 built with all the goodies(wide ratio 1st&2nd,rollreized,bla bla bla) 8 or so weeks later I recieved it,put it in and what a peace of crap,#1 no gears at all,after reving it up it would go into drive then all the gears would come & go as they pleased, after calling the builder he suggested some "testing with vacum gauge & pressure gauge,ok so testing was in progress and in the middle of second gear it hit nuetral and the engine hit rpm's olny reserved for humming birds and model airplane engines, now I have a tick/knock in my 427 stroker. so the builder sends me out a valve body and now it shifts(not crisp) and my torque converter I wanted with stall slightly above stock is auctally LOWER then stock.