1996 yukon runs rough in gear

[Copster]

Hello everyone, this is my first post. I just purchased a 1996 Yukon with the 5.7 vortec. When I stop in gear the motor runs real rough. If I take it out of gear in park or neutral it runs great. There is no hesitation after you hit the gas in drive or reverse. It only happens when you are stopped in gear with your foot on the brake. Time you hit the gas it runs great. Can anyone help with this? Thanks.

 

[ezdaar]

look for leaks in the power brake booster line, especialy the plastic 90* that goes into the booster and the grommet that it slides into..

Quick test to find out if brake booster has internal leak, after determining the line is good.
Remove line from booster, plug it. to no vac leak to engine...

Put in gear while on brake.. no stumble.. booster is leaking, still stumbles, look to IAC valve first then random vac leaks on motor.

 

[SunlitComet]

fellow Motor Trends Truck of the year owner. Pic, Pic, Pic, Pic, Pic, Pic.

 

[Copster]

Thanks I will check that tonight and give an update.