1999 Silverado Stumbles

I have a 1999 Chevy Silverado 4x4 with 64k miles, 5.3 L engine and automatic tranny. The truck "stumbles" at different times. The problem generally occurs when I first start the engine and put in gear. Once I begin to give it more throttle, the problem starts to dissipate. During acceleration at low rpm and slight throttle it also stumbles/bucks. The truck seems low on power in overdrive but when it kicks down, it seems to be ok. I have changes plugs and fuel filter. No trouble codes or check engine light. The dealer was unable to find anything wrong...it was working well when I took it in. Any Ideas? I can recreate the problem by holding the brake and throttle, loading the engine. Mostly this is noticed under 1500 rpm.

Reply to
Scooter
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How long has it been since you replaced the rotor and cap? When my 96 Silverado starts to buck and stumble when cold that has been the cure twice now. If you are getting P0300 codes(multiple misfire) that is a big clue too. Cap, rotor and possibly wires are an easy fix. I also learned to stay away from the cheap wires too. Go to a real parts store and pay the money for their best quality wires.

Reply to
Mike Copeland

There is no rotor and cap. On the 99, it has 8 coils.

Reply to
George

Reply to
Steven

What do you mean "cleaned Professional"?

("stumbles" at different times.) ------been there ----

I've used the STP injector cleaner (I think it's just acetone) and I've had other vehicles professionally cleaned using either stuff that came in what looked like undersized bernzomatic bottles and also by an inline fuel can/bottle, I wasn't impressed by the overall results, in either case, both MOPARS, the final solution for the Caravan was to replace the fuel pump and for the Jeep XJ it was the CPS sensor.

Now I've got a "just off idle-in Drive only " stumble with a new-to-me low mileage 1994 K-Blazer 350 Auto., Not sure if it's the engine or the 4L60E (4L80E?) transmission. I'd be really pleased if a good injector cleaning would cure the problem. David

Reply to
David Anderson

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