Rough Idling and Acceleration Problems
Just a couple of days ago, my 91 Sierra 5.0 liter (60K miles) developed a problem. It has two components which are undoubtedly related. First, idling is a problem. It will almost die, then resume normal speed. This cycling continues, especially when the engine is just started. It appears to improve, but not go away, once the engine warms up. The second is that acceleration appears to be poor, at least poorer than normal. This hesitation continues even with a warm engine. It might not be terribly noticeable to someone who has not operated the vehicle. The truck is still driveable, but certainly not as smooth as a few days ago. The things I have changed include: new PCV, new spark plug wires, new distributor and rotor, and new fuel filter. I added a can of engine cleaner thinking that I might have a problem with dirty injectors. I've only used a few gallons of gas since addition of the cleaner so it may not have had time to do its work. The timing checks OK. This may or may not have any relation to the problem, but my wife ran over a curb on the driver's side just before the problem was first noted. She didn't think anything scraped bottom but she did comment that it was quite a jolt. Any ideas about what to try next?
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