I'm fixing this Chevy for a guy right now that does the same thing. This is what I have done
Change or check the PCV and all vacuum hoses.
Cleaning the throttle body. Use T-body cleaner or some Brake Cleaner if you already have it. Spray it into the TB to clean all the crap out. There will be black and brown crud all over it if it's never been cleaned. Then change the fuel filter and maybe run a bottle or 2 of Techron thru it.
Also check and make sure the cap, rotor, spark plugs and wires are in good shape. They weren't
I also am running an AutoRX clean cycle with fresh oil and filter. I also changed the air filter.
After I did all that, this Chevy with 160k miles on runs like new. He hasn't picked the truck up yet, but I'm sure he'll be pleased. I ran terrible before
Thanks a lot Huhwhye, I will check all the vaccum hoses and check my air filter to see if it is dirty.
