Sputters at about 40 tachometer starts going crazy

2000 GMC SIERRA
167,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC
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SHERI ALLEN
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Sierra 3500 had motor and transmission replaced 2 years ago. ran great then fuel pump went out, replaced it, the cap, the rotor, plugs plug, wires, coil. now it idles great but once you drive about 10 miles it starts sputtering backfiring kinda exhaust smells awful. but then you let it sit a minute and it’ll run fine again. the gauges when the key is off mark everything as if it’s on when key is on all are at mark they should be when key is off. we have spark, we fuel. so what could be causing this? we live about 50 miles from the nearest town so it’s not like we can run in to the parts store or junk yard real quick. please if anyone has had this problem before or knows how to fix it let me know. This truck was a Cab and Chassis a utility bed was added later 5.7 vortex 1 ton 3500 4 wheel drive.
Jul 27, 2019 at 7:46 AM
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STRAILER
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When you did thew tune up did you use AC Delco parts? if not I would order all AC Delco, plugs, rotor, cap, wires. Here is how to do the job correctly with a code scan guide which we should do as well.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down these guides and report back.
Jul 28, 2019 at 5:15 PM
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SHERI ALLEN
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I’m sorry but we live about 50 miles from the nearest town and our F250 is getting a new transaxle so we’re like stuck here the tune up was done 2 weeks ago all oem parts were used the weird thing is it was half a—Ed running before the tune up then it didn’t run at all until yesterday it started ran went approx 25 miles down our dirt road and then it started missing real bad sputtering wanting to stall then finally did we have 60 plus psi for fuel but no spark to the coil almost as if something jiggle lose or shorted out or something I don’t get it
Jul 28, 2019 at 7:26 PM
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STRAILER
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It could be an ignition module going out. but let run the codes to see what comes up. please refer to the link above and report back. Also in 2000 there is not suppose to be a distributor can you confirm you have one please?
Jul 29, 2019 at 10:02 AM
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SHERI ALLEN
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Yes, we have a distributor. we had to replace it along with the engine 2 years ago.
Jul 29, 2019 at 10:25 AM
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STRAILER
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Lets run the codes to see what comes up and if no codes are present lets replace the ignition module and coil. here is how in the diagrams below:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Check out the diagrams (below). Please let us know what happens.

Jul 30, 2019 at 10:11 AM