Truck running poor

1994 gmc jimmy 4.3vortech runs poor .Itook truck to shop they said egr valve was dirty .paid to have cleaned Picked up truck truck barley runs . The shop wants another $100 to look at again.which i wont pay because thats why the truck was in there in the 1st place.

took truck home iput new plugs ,wires ,cap ,rotor still runs has a strong miss at all times gas mpg down to 10 mpg should be at 20mpg. Iwont be going back to that again . any ideas ?

forgot to mention when taking off from stop light it seems to have no power like its running on 1 cyl

  You need to have the codes read assuming your truck has a computer, I believe it does. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. It likely will have a format like P1234.

hello. had codes checked.I had a local parts store pull the codes .no codes are being stored. checkengine light never comes on except on start up like they should.thanks

Flush gas tank, replace fuel filter.

It sounds like the timing might be way off. A shop set one of my ford trucks a 8 ADC instead of BDC and it barely ran. You might try turning the distributor when its idling to where the engine picks up speed, then back off just a bit. Then you can put a timing light on it.

you can not just turn the dist,the computer will fix it all must disconnect the wire . nuff said ,its called EST bypass.

Have the fuel pressure checked. The ECM doesn’t monitor the fuel pressure. Also, could be plugged up injectors. These will not set a code if the injectors are getting electrical feedback. The ODB system in this truck is not the most sophisticated. I believe old-fashioned diagnostics are the only way to go.