Sierra Vibrating And Running Bad

[estein00]

Ive got a 99 sierra 5.3 and when idiling the truck vibrates very bad. The rpms do not dip or rise they stay the same, also when starting off maybe at a stoplight the truck hesitates and has a hard time getting going. Once above 30 mph the service engine soon light flashes and then stays on once below 30. This started happening only when it was cold and the truck was not warm, now it happens all the time. Any help is appreciated!!

[gnet158]

Going to take a shot in the dark here but when was the last time you had your:

 

1. Plugs & wires changed

2. Fuel system cleaned

3. A look at your throttle body

 

If it's been awhile or they are due then that's where I'd start. You could sea foam your truck and hope that's it.

[thebandnerd03]

these trucks are known to have issues with carbon build up on the throttle valve set up. have your intake and fuel system cleaned and this should help. also it wouldnt hurt to have it scanned to make sure you are not running to rich or to lean

[estein00]

thanks guys i appreciate the help.

these trucks are known to have issues with carbon build up on the throttle valve set up. have your intake and fuel system cleaned and this should help. also it wouldnt hurt to have it scanned to make sure you are not running to rich or to lean

[owenbyc]

yup i bet the code would be multiple cylnder misfire. you should def check the code or codes and go from there. i had a 2000 gmc jimmy biggest piece of you know what. i didnt have it long and it would not want to get going from a start it felt like it would spit sputter and surge from first to 2nd then a little to 3rd. i changed the plugs wires cap and button. cranked her back up and shes was running like a champ. so good luck