1995 Chevy K1500 4.3L V6. When starting the engine it has an inconsistant idle and will sometimes shut off. If it does stay running, it will idle low then high and correct itself or stall when I put it in gear. It is hesitant when speeding up, feels like a loss of power. I have changed the Spark plugs, wires, cap and rotor, fuel filter, air cleaner and have put some dry gas and fuel injector cleaner in it. Also have cleaned out all of the vaccuum lines. Have tried to time it too, but nothing seems to work. Any ideas? Thank you.
The first thing you need to do is stop changing parts and putting additives in the fuel. There are lots of things that could be causing your symptoms. It sounds like you have reached your limit on this one, take it to a professional.
While it may be that none of the things you have done so far have rooted out the problem, they are all perfectly fine basic maintenance things to do. Here are a couple of suggestions that cost next to nothing and may help.
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vacuum leaks could easily cause this but are notoriously hard to find. Take a torch - butane or propane - DON’T light it - just turn on the gas and feed it around all over wherever you see vacuum connections. Use the vacuum system diagram on the underside of the hood to make sure that you look at everything. If you get the fuel from the torch near a leak the engine will respond.
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Check the connections for your idle air control valve. Also pull the valve and clean it - usually very easy. Use some throttle body cleaner and have a new gasket handy.