the lady just bought it used. it is a 96 GMC with a 5.7 and 4x4. it was regularly serviced at a repair shop in spangle. we have run two cans of seafoam through it because it sat for two years. the only check engine light that came on was for low voltage to the o2 sensors. they were both changed, didn't help. battery voltage is up where it is supposed to be. the fuel pressure was checked and with the key on engine not running it was 55 psi until you turned the key off then it dropped to zero. with the engine running it was between 60 and 65 regardless of throttle position. the trans is starting to slip a little and when you put it in reverse it hesitates then slams into gear the fluid is up to full. it is getting great gas mileage. a tune-up was just done just before it was set aside. everything tune-up wise looks new. there must be a bad sensor or pressure regulator that is bad or something. it is getting frustrating.