a co worker of mine has a 02 with 5.3 and 150k and its has a rough idle for about 5 seconds after the inital start . then it idles smooth ? any ideas of what it might be . he put bosh plugs in it and i told him to run the tr5 and that didnt work . no check engine light . i recomended cleaning the mass air sensor.

 

Clean MAF sensor, clean the TB, sea foam it.. Put the stock NGK plugs back in it.. Should do the trick

 

fuel pressure regulator on driver side fuel rail, pull the vac line off while the truck is running and watch the nipple on the regulator for a few minutes. I'd be willing to bet you'll see fuel start to seep out, and a new regulator should cure it

 

thanks we will give it a look

 

My truck does the same only when cold but for about a minute. When it's below 40 I also get a random cyl missfire won't do it at all during the summer

 

Thanks 454 it was the fuel pressure. Regulater runs great now.

 

Glad to help