1996 Chevy Truck miss and service engine light

1996 CHEVROLET TRUCK
175,000 MILES • V8 • 4WD • AUTOMATIC
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MADMICHIAL
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At highway speed (65-75) I have miss and if i drop from overdrive to 3rd it gets worse and jerks. the service light comes on and blinks. the code given is p0300.
I have changed plugs,wires,cap,rotor and o2sensors
I tested fuel pressure it is good and stays constant. TPS voltage is smooth climb w/no dead spots


This is my second time asking this question on the site, The first time I got no help so this time I cant donate much. sorry
Nov 24, 2008 at 3:44 PM
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DOCFIXIT
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Code is multiple/random missfire this is a tough one to diagnose via internet. What have found out in past is a fuel problem ie. low pressure, clogged filter or injectors. Start with fuel pressure and give ignition a look. If all checks out then a faulty crankshaft sensor or camshaft sensor will cause P0300.
Let me know
Nov 24, 2008 at 3:52 PM
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MADMICHIAL
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Can these sensors be tested?
Nov 24, 2008 at 4:25 PM
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DOCFIXIT
  • CAR REPAIR CONTRIBUTOR
  • 18,828 POSTS
With a diagonistic scanner. You can use a DVOM on AC volt scale and see if a signal is produced. Not as reliable as the scanner.
Nov 24, 2008 at 4:51 PM
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