I had a bad TBI gasket on my 1989 5.7 Chevy pick-up . It was ideling high and using a lot more gas . Also at work the 4.3 Chevys get stuck EGRs at times . But on them they wont Idel and just keep dieing out . Some times you can tap on the EGR valve to drive them into the shop . But then we replace the valve .