Chevrolet Repair: bad running engine, vacuum leaks, chevrolet silverado

Question
what should i do to solve a problem with my poorly running truck? the truck will not start unless the gas pedal is floored, the truck does not idle well either, to keep it running you have to constantly be pushing the gas pedal down. the truck sounds as if it is surging, like running then dying then running...seems to be sucking gas. 1989 chevrolet silverado pu, 350 ci automatic tranny, throttle body.

Answer
Hi Chris,
Fuel pressure comes to mind. It is imperitive to have about 12 PSI at the throttle body.
I like 13, but it will run on less.
The lower it gets, though, the worse it will run.
Dirty fuel injectors, vacuum leaks, sensor problems...they are all possibilities.
If it runs good when cold, but then starts having the problem after warm up, sensors would be more suspect, but if it runs the same hot or cold, the electronic side is minimized, because the sensors don't come into play till the engine is at operating temperature.
A bad temp sensor could shoot down that theory though, by tricking the ecm into thinking the truck is at op temp, and going into closed loop.

The EGR valve, right behind the throttle body, is a major source of vacuum leak if it happens to be dirty and not closing. It should be removed and cleaned, and tested for proper operation.

I am assuming plugs, wires, and distributor cap are in good shape?

There is always the possibility of worn timing chain.

Van