92 Regal with 4t60 trans behind 3.1 engine. My speedometer stops working and the service engine light comes on then goes off and on as I am driving. The car wont idle below 1000rpm while speedometer is not working. Wont restart without pushing down throttle slightly. Engine runs and accelerates no problem otherwise. The tach will drop down here and there then work again also. I have replaced the speed sensor and put in a new fuel filter but no change. I hope someone has other ideas. Oh I am going to check the grounds tomorrow for a loose connection. Let ya know what i FIND.