2005 Chevy Astro ENGINE STUMBLES OR HESITATES

2005 CHEVROLET ASTRO
88,000 MILES • 6 CYL • 2WD • AUTOMATIC
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MARTY809
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I HAVE REPLACED THE PLUGS,PLUG WIRES,DISTRIBUTOR CAP,ROTOR,TPS SWITCH,GAS FILTER,O2 SENSOR THE DOWNSTREAM ONE,AND THE TEMPERATURE SENSOR IN THE HEAD. I HAVE SWITCHED THE 93 OCTANE SUNOCO GAS TOO. WHEN I START UP IN THE MORNING, ENGINE IS COLD. IT IS OK AFTER ABOUT 5 MINUTES OF DRIVING AND IDLELING. THEN I TRY TO LIGHTLY ACCELERATE AND THE ENGINE STUMBLES IT IS LIKE IT IS MISSING.THE CHECK ENGINE LIGHT DOES NOT COME ON.
WHAT ELSE COULD BE THE PROBLEM. IT SOUND LIKE THERE IS SOMTHING CAUSING THE MIXTURE TO BE TOO LEAN.
BOB
Sep 9, 2009 at 9:10 PM
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JACOBANDNICKOLAS
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When you say lean, it makes me want to tell you to check for vacuum leaks. Have you? Also, have you checked fuel pump pressure? If not, do so. Here is a how to:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

You will need a gauge, but most parts stores will lend or rent them.

Let me know what you find.
Sep 9, 2009 at 10:43 PM
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MARTY809
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YES I CHECKED THE FUEL PRESSURE IT IS 61PSI THEN GOES TO 58-59 PSI. VACUUM IS GOOD ABOUT 20 INCHES OF VACUUM.

ANYTHING ELSE.
Sep 10, 2009 at 8:12 PM
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JACOBANDNICKOLAS
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Have you checked the EGR valve?
Sep 10, 2009 at 9:00 PM