Car idles very high then drops down and will not stay running. spits and sputters when crusing. misses and jumps really bad when under any load. have done complete tune up. NO vaccum leaks.

CK FOR VACUUN LEAKS

What year is it? Your symtoms suggest oil contamination from bad fuel pressure regulator.

Starter drag or the alternator is g

Ck your alternator output, should be between 13.8 and 14.2 volts, A bad alt will cause the battery to discharge when driving, Once voltage drops to a certain level (9.8 I think ) the ecm starts to shut down causing all kinds of strange problems, like running bad ,trans not shifting right, even the radio ! It happened to me in my 95 chev p/u

Does it use spark plug wires or individual ignition coils for the each plug?. My 98 intrepid uses coils and occasionally I have to change them out cause it would start to miss when normal temperature was achieved. If it uses wires, try replacing them, along with the spark plugs.

For engine misfiring problem check the help links mentioned below. Click the link below to go through the troubleshooting procedure :---- Engine misses and truck jumps? Hard to down shift? Issue with high gear only? http://technoanswers.blogspot.in/2012/02/engine-miss-and-truck-jumps-hard-to.html

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Bad miss at idle?

http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

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While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

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Engine Misfire codes for car?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html
Engine Misfire codes?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

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Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

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Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

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This will help.

Thanks.

For engine misfiring problem check the help links mentioned below. Click the link below to go through the troubleshooting procedure :---- OBD-II Trouble Code P0300? http://schematicsdiagram.blogspot.com/2011/12/obd-ii-trouble-code-p0300.html
---------- Engine misses and truck jumps? Hard to down shift? Issue with high gear only? http://technoanswers.blogspot.in/2012/02/engine-miss-and-truck-jumps-hard-to.html

-----------
Bad miss at idle?

http://technoanswers.blogspot.com/2012/01/bad-miss-at-idle.html

-----------
While stop engine idles like cylinder missing?

http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html

------------
Engine Misfire codes for car?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html
Engine Misfire codes?

http://schematicsdiagram.blogspot.com/2011/12/engine-misfire-codes-on-chevrolet.html

--------------
Misfire on cylinder 4?

http://schematicsdiagram.blogspot.com/2011/12/misfire-on-cylinder-4.html

-----------
Oil on spark plugs and car misfires?

http://technoanswers.blogspot.in/2012/02/oil-on-spark-plugs-and-car-misfires.html

----------

This will help.

Thanks.

Fuel pump may not supply enough pressure to run engine, but it could be a pluged fuel filter as well. you should get the code pulled out of the computer this will tell you exactly what is wrong or at least narrow down what is causing the problem. It could also be either bad gas with water in it or bad timing or wrong firing order.

I have the same problem on my 95 grand cherokee laredo. Sometimes it starts out fine and after about 10 miles it starts spitting and sputtering. Then after a while it seems to clean out and run fine again for a little while. Then other times it starts out spitting and sputtering at the begining. I changed the fuel filter and that was not it. It is a 4.0L 6cyc. Any Ideas?

Thanks,
Broken Arrow, OK

Have you tried the fuel filter?