'97 GMC 350 Engine Performance

My GMC suddenly started cutting out under load. I've noticed it occasionally missing in 3rd gear and OD so far and tried to get it to do it in 2nd yesterday afternoon but never could. Doesn't idle rough
(had it tuned up about 5k miles ago at the dealer) and it's doing this around 2300 RPMs, generally on a slight uphill grade.
It ran so smooth in 2nd yesterday that I'm wondering what 'emissions' type devices might be causing something like this. (noted the missing BTW as something that almost feels like a sharp wind hitting the vehicle with a momentary dip in the tack reading). Any ideas folks?
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Wires. Fuel Filter. Don't jump to "emissions type devices" or anything else until you cover the basics.
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dahpater wrote:

the fuel tank. At less than full load, all was well. Max load caused a stumble. Isolation hose between pump & delivery tube leaked by hose clamp.
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I agree on the fuel pressure:
But, on the transmission slipping from second to third. If it's a 4L60E or 4L65E, there is an issue with the pressure control valve for the lock up torque converter. I would have this checked, before it costs you a total rebuild. With lots of hard parts.
Now you can just have the valve body machined, or use a shift kit, with an insert type valve.
RK
wrote:

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sounds like the fuel pump is not working 100%. What are your fuel pressure test readings?
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No where in his post does he mention "transmission" problems! There is no mention of "slipping from second to third". He is discribing a "running" problem.
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cover wrote: (1997 GMC 350 Engine Performance)
My GMC is cutting out under load. It occasionally misses in 3rd gear and OD but not in 2nd. It does this at around 2300 RPM, generally on a slight uphill grade. When it misses it feels like a sharp wind hit the vehicle with a momentary dip in the tach reading). It idles smoothly (dealer tuneup 5k miles ago). Any ideas? ________________________________________
Wires. Fuel Filter.
Don't jump to "emissions type devices" or anything else until you cover the basics. dahpater ________________________________________
I had a similar situation. It turned out that I was losing fuel pressure inside the fuel tank. At less than full load, all was well. Max load caused a stumble. Isolation hose between pump & delivery tube leaked by hose clamp. "syoung" _________________________________________
It's probably not the fuel delivery system because it only happens at part throttle.
It's probably not the high voltage system (wires, coil, distrib, plugs), as it doesn't happen at full throttle.
Some other possible causes:
-- Sticking IAC -- Intermittent Igniton Module failure. -- Trans downshifting late. -- TCC engaging too soon under load.
Trans and TCC errors could result from erroneous load sensors such as manifold vacuum or throttle position.
Good luck.
Rodan.
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Yes, fuel, wires will cause this problem!

He didn't say he has transmission problems!

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<dahpater yahoo.com> wrote:
He didn't say he has transmission problems! _____________________________________________
<dahpater yahoo.com> wrote:
Nowhere in his post does he mention "transmission" problems! There is no mention of "slipping from second to third". He is describing a "running" problem. _____________________________________________
Thank you for your helpful contributions.
Rodan.
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