car stumbles/stutters/hesitates upon acceleration from dead stop or increasing speed sometimes

2003 CHEVROLET VENTURE
75,000 MILES
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RONBO1
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new fuel filter,newplugs/wires/o2 sensor,dry gas,injector cleaner,no codes,certified mechanic found no misfires in computor history, 52psi gas pressure gauge reading engine off key on,55psi at idle,58/59psi on accelaration to say 50mph, even stumbles/hesitates at 58/59psi..could it be coils? fuel pressure regulator holds vacuum ok, sometimes it runs fine. van has electronic egr. depressing on accelerator when stumbling causes engine to perk up and car gets going.with brakes locked and gas pedal floored rpm changes by around 500rpm about.
Mar 17, 2012 at 3:04 AM
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FIXITMR
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very doubtful coils at fault since no misfires.
Mar 17, 2012 at 4:01 AM
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FIXITMR
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does it feel sound like misfiring or just loss of power?
Mar 17, 2012 at 4:49 AM
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FIXITMR
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needless to say, live data monitoring would help zero in on issue.
Mar 17, 2012 at 5:11 AM
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RONBO1
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does not sound like misfire...is loss of power...surges up and down i would say about 4-500rpm approx it has no tach.we used to say it was "breaking up" when u get on the gas.
Mar 17, 2012 at 7:03 AM
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FIXITMR
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live data monitoring would be advantageous. wonder if auto chain stores can do that?
Mar 18, 2012 at 6:42 PM
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RONBO1
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i am giving up on it and dropped it off at the chevy dealer this evening.....hopefully i wont have to take out a second mortgage to pay them if they can find out the problem...thanks for ur help.
Mar 19, 2012 at 1:04 AM
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FIXITMR
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let us know how it goes.
Mar 19, 2012 at 8:05 AM
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RONBO1
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dealer says it s catalytic converter plugged wants 1300.00 bucks lolo takin to a mom and pops to see what he says..
Mar 21, 2012 at 2:26 AM
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CHEVYFORLIFE
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If it isnt a cat maybe look at a pressure control solenoid. Causing a shudder under load when hot. Pretty common problem with the transmission in your van.
Apr 4, 2012 at 2:08 PM