I have a 1991 cherokee laredo 4.0 H.O. with automatic tranny, the transmission seems to start off in second gear when at a stop it doesnt have any power off the line unless you downshift into 1-2 gear it works fine. but when in drive it doesnt, also when you put the petal to the floor it doesnt downshift, i have changed the throttle positioning sensor, adjusted the tv linkage, and even tried another Transmission control unit... none of these worked any ideas?