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Pete, Auto Service Technician
Category: Chevy
Satisfied Customers: 27918
Experience:  14 years GM dealer Technician.
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Have a 99 Yukon SLT 4x4 with a 5.7. Started having issues a

Customer Question

have a 99 Yukon SLT 4x4 with a 5.7. Started having issues a couple weeks ago, particularly with the engine missing intermittently over bumpy roads. As I'd hit the bumps, my rpms would drop to nothing, gas and oil gauges would move erratically, but no loss or dimming of dash, stereo or headlightsor any other electrical symptoms, and no SES. As the problem worsened, I began being bogged down and almost stalling when accelerating from a dead stop unless I was light on the gas. Within the last two months I've installed direct fit cats, a new fuel pump, tuned up (wires, plugs, rotor, O2 sensors), replaced the crankshaft position sensor. When the problem started, I checked the wiring harnesses and connectors with the truck running and couldn't replicate the symptoms while not under load. Figuring I'd eliminate a few possibilities at once I changed the idle air control valve and ignition coil, cleaned the MAF and throttle body, and checked the EGR for build up (it was reletively clean, no blockages). After I finished and took her out on the road for a test run, I got a block from home and stalled. Truck started fine, idled fine, but once I put it in drive and hit the gas, it died. Tried starting and driving several times with no success, but put it in reverse and she ran like a champ all the way home. This is where I am now. Truck starts, idles fine, but when I put it in drive and hit the gas it dies. Reverse works perfectly and seems unaffected and still no codes or SES.
Submitted: 1 year ago.
Category: Chevy
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

If you havent yet check the battery cables at the battery as well as to where they run to from the battery and at the under hood fuse panel and interior fuse panel for any loose,damaged or corroded wiring.Check the ground straps on the engine and cylinder heads.This sounds like a major loss of power or ground causing this fault here as I have seen and had to repair before.If this is all checked and found to be o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete