I just found out that the hypertech chip in my 87 5.0 5spd is for a 5.7 auto..Bought the car couple months ago.But been having problems with it idling right since.i keep getting Veh Speed Sensor code too! Speedo works fine.replaced buffer,and it was ok for 4-5 days til the code came up again.Could that chip be causing my problems and the code too?? I was told it ran good for few months last summer,but started acting up towards fall.

Thanks

 

I would think it would contribute.