99 4.8 rough idle

I have a 99 silverado with the 4.8 w/186k on the clock. I am having an issue with rough idle and hesitation on cold start up. Once the truck warms up the idle and hesitation go away. I have replaced the PCV valve hoping this fixed it, but it did not. I have also cleaned the TB and the MAF. Any help would be appreciated. Thanks.

I have a 99 silverado with the 4.8 w/186k on the clock. I am having an issue with rough idle and hesitation on cold start up. Once the truck warms up the idle and hesitation go away. I have replaced the PCV valve hoping this fixed it, but it did not. I have also cleaned the TB and the MAF. Any help would be appreciated. Thanks.

cold start would be ECT needs replacing . these go out of proper resistance vs temp at the 10 year mark. this I guess would be this since after warming its normal.

the other possible problem would be dirty fuel filter/ fuel pressure. pressure test for correct amount. you need more pressure on a cold start vs warm start.

cold start would be ECT needs replacing . these go out of proper resistance vs temp at the 10 year mark. this I guess would be this since after warming its normal.

the other possible problem would be dirty fuel filter/ fuel pressure. pressure test for correct amount. you need more pressure on a cold start vs warm start.



Thanks J