1998 Chevy Suburban Running Ruff

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1998 CHEVROLET SUBURBAN

Engine Performance problem
1998 Chevy Suburban V8 Four Wheel Drive Automatic 162K miles

Motor Running ruff sometimes. DOes not matter time of day. Most of the time when it happens is after I have shut it off and come back out to start it in a few mins.

If I step on it a little hard and let off it runs smooth again until the next time.

I have replace the fuel injectors. Plugs, cap, wires. Wires twice.

Also had it hooked up to a computer and the fuel pressure is at 60 to 80.

Also replaced the front 02 sensors and both catylitic converters.

All my plugs are half tan and half wihite. Cleaned up all the air sensors put in all new filters and new gas filter.

Don't know here to go next. Please help.

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Clean out the idle air control and EGR valves and test the throttle position sensor.

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Wednesday, July 28th, 2010 AT 4:02 PM

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We did this as well and still does the same thing. Today I did several short runs going to different places. Everything was going well until the last stop. I shut it off and went in and picked up some things I needed. Then went out and started it up and it was back to running ruff again. So I stepped on it a little a couple time and it smoothed out and I went on my way.

As I said before it does not always happen. It might happen several times a day or not at all. I truly hope we can figure this out.

Please keep in mimd the the spark plugs are all have tan and half white. I can't help but think this is a clue.

Thank you for replying.