My 2000 expedition will trip ck susp light when idling sitting still for about 4-5 minutes, during this time compressor cycles on / off before tripping light. Most recent condition is that when riding down the highway the ck susp light will come on and the rear susp will drop slowly in about...

I have a 1989 F-250 5.8L, I have replaced or tested with "none good" all sensors and computer. Truck does not seem to have any vaccum leaks, no codes are present. If truck idles for more than 61 seconds (throttle untouched) a surging starts. Cat is unobstructed, timing is correct, base idle is...