I have an 85 gmc Sierra classic, it starts hesitating
with acceleration at 45mph, now when I got to
start it it starts at a high idle roughly 3-4000 rpms,
im thinking it may be a vacuum line but im not
positive, can anybody help?
It is probably a miss, check cap & rotor, wires and spark plugs.
How long since a tune-up? Any applicable trouble codes? Your obd1, you should be able to check some codes, yourself, if there are any. Make sure throttle valve is closed. Block off the mouth of the throttle body, it should kill the engine. If no effect on idle, you are getting false air in there from somewhere.
Im not real sure I got the truck about 3months ago, I know the plugs are shot and not gapped correctly, it has a few vacuum leaks and the timing is off just a hare, its been this way since I got it and it just started doing this today, I will check everything and see how it goes thanks
Any of that could be causing your problem, Giver a good tune up.
Thats my thoughts exactly, thanks for your help I really appreciate it