99 Burban Rough Idle and stumbles at 45 mph

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by 2lock, Nov 11, 2012.

  1. 2lock

    2lock New Member

    Hey all am new here and have some questions. We have a 99 Burban 1500 5.7 with 126,000 miles. The problem is the idle is rough and 'stumbles' when going about 45 mph when trying to accelerate. When I say stumble it's like riding on the rumble strip on the side of the road but more intense. It every once in awhile throws a code for 4th cylinder misfire...not always. It also stumbles when I slow down then try to accelerate. Can hear spark knock at that time. Any suggestions would be appreciated.
    What's been done
    plugs and wires x2
    fuel spider
    fuel pump and filter
    spark knock sensor
    egr valve
    coolant temp sensor
    map sensor
    ignition module
    throttle position sensor
    cam position sensor
  2. Quikfire

    Quikfire Member

    I had a similar issue on a 99 burb last year. It turned that my distributer cap and rotor were in sire need of replacement. It was a fairly simple fix and relatively cheap. I would at least look at the inside of the cap. Hope that helps.
  3. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    [MENTION=57814]2lock[/MENTION] , any luck on a fix?
  4. 2lock

    2lock New Member


    no luck checked the distributer cap and rotor all good....driving me crazy
  5. nadcicle

    nadcicle New Member

    Had similar symptoms myself. I noticed you done the spider assembly. I would probably lift the upper intake manifold and check for extra clean spots and smell of fuel. My problem was a leaky fuel pressure regulator on the passenger side dumping fuel right in to number 4 and flooding that one out.

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