1992 Chevy 3/4 ton pickup. Repairs- New spark plugs / plug wires and oil change. Newer air K&N air filter. Added fuel injection cleaner and cleaned off throttle spring.
Question = Purchased the truck a month ago and it didn't get driven much before it was sold. Truck hesitates when coasting downhill but doesn't seem to do it on level ground, has a hard time running when you try restarting it after it is hot, and also seems to idle to fast. Not sure if all of this is associated or not.
Answer: A few of the problems you describe sound like low fuel pressure or a vacuum leak. Hesitating going downhill the engine and throttle is at idle. A vacuum leak can cause the hesitation you are feeling. Hard running when started hot can be a vacuum leak or low fuel pressure problem. With a low fuel pressure problem on unlevel ground, maybe there is something in the tank floating around and blocking the pickup. The only way to tell that would be to check the fuel pressure and if it goes low you may need to remove the gas tank and look for dirt or something else in the bottom.
Check for carbon on the idle air control valve. This is also a possibility. That can also cause a high idle, where as a vacuum leak can too but usually a low and unstable idle.
Some common areas of a vacuum leak are any of the vacuum hoses, the brake booster, the throttle base gasket, etc.
Using brake cleaner while the engine is running can help find that. The engine idle will surge if you get near the leak. But, be very careful as brake cleaner is very flammable.
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