I have a 97 z28 with a new A4 with a revmax 3000 stahl converter. Has been shifting fine for months. Now it doesn't want to come out of D1 unless I feather the throttle. The rest of the gears are fine. Just the first to second, it wants to hold it till redline. Any suggestions? Vss? Tps? Or bad solenoid. Kind of lost, would appreciate any input