Engine Performance problem
1989 Toyota Pickup 6 cyl Four Wheel Drive Manual 150000 miles
The truck idles fine until you step on the brakes. Then the idle drops and fluctuates badly. No vacuum leaks. Once you unplug the brake switch the problem dissappears. It only does it when the brake lights come on at idle. ECU checks OK and all grounds are good and the harness seems to be in good shape.