I have a 03 5.3 vortec it has a rough idle and if you rev it it wants to die when you reliese the peddal.

Marvin

• 85242 Answers
• Posted on Nov 04, 2008

SOURCE: idles rough

Check for engine vacuum leaks, most likely around the upper intake manifold arear, look for vacuum hoses that have come off or a missing vacuum port block off cap at the rear of the engine drivers side, large cap.

SOURCE: 4.3 vortec runs OK cold, runs rough or dies warm

Your cylinder 4 misfire would most likely be a bad plug wire. And it is common for cars to have driveability problems with a crankshaft sensor code, esspecialy after the car has warmed up that is when you will notice the problem. The crank sensors are pretty simple to change and relativley inexpensive maybe around 40.00 for the part. If you look around the crank shaft pulley you will see a sensor with usually 2 bolts and a couple of wires attatched to it. If the vehicle gets to a point that it won't start, spin the motor over watching the tach on your dash and if it is not moving while cranking that means the sensor gave out. Good luck. swiftautorepairs.com

mike james

• 302 Answers
• Posted on Oct 04, 2009

SOURCE: rough idle, can't rev, unplug map sensor it runs

GO 2 AUTO ZONE AND HAVE THEM SCAN UR SYSTEM THIS SERVICE IS FREE, SOUNDS LIKE U HAVE BAD MAP SENSOR

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SOURCE: car seems to idle rough. almost dies then the car

you need to have an OBDII code scanner to read the error codes or codes for the check engine light being on. sounds like the mass air flow(maf) sensor is the culprit. also possible is either the throttle position sensor(tps) or idle air control(iac) valve. the OBDII code scanner will tell you in a PXXXX error code to help you pinpoint the problem. (the XXXX is the numeric error code and the P stands for powertrain.

SOURCE: 96 gmc vortec will not start

I AM LOOKING AT TIMING ISSUES OR INTAKE MANIFOLD LEAK.OR EGR VALVE STUCK OPEN.