I have a 2000 5.3 liter 145,000 miles, it's runnning very rough, vibrating at acceleration and idle, its worse than a dropped cylinder. It also emits a bad fuel type smell in cab. I've filled up at a gas station with higher octane fuel but its still doing it. I dont think its electrical because of gas smell and I did a tune-up late last year with new plugs and wires. Any fuel components that should be replaced. Its been doing this for about 2 weeks now and multiple different fuel stations, I dont think its bad gas from any one particular station

 

Did you try fuel filter?

 

Do you "top it off" when you fill your gas tank? Fill it to the nearest dollar? Overfilling the tank can result in flooding of the evaporative canister. This could result in the passenger compartment smelling of raw gas.

Vapor lock may be an issue, as well as bad gas. A change of the evap canister charcoal filter may be in order. While performing the filter change, try to eliminate any gas found in the canister, and the vacuum tubing.

Of course, the rough running engine and the flooded canister may just be co-incidence.

 

I have been getting vapor lock also, I have to wait about ten minutes before truck will start again. Also the check engine light is on

 

get him to any parts store and READ CODES!! then post here, we'll help.
you have no ignition in one/several cylinders, or one of the injectors is stuck open, or fuel regulator gone bad. regulators are known(what's not?) faulty parts on those trucks.

 

chevy cant make a fuel system for ****,you probably have a fuel leak... sniff around the back of the engine and see if you can find fuel dripping around, also do a fuel pressure check, you may have a bad fuel pump or regulator, and when it is running look at the exhaust, check for black smoke. just for ****s pull the oil cap off and check for blow-by.