Hard To Start

[medievalsoldier]

Ihave a 2002 GMC Sierra Z71 with a 5.3L

 

When I start my truck in the am it will miss fire and it sound like it going to stall.

The TAC will jump to 2000 rpm then drop to 1500 then 1000, and then 500 Rpm then it will jump to 1500 then back to 800 rpm. I did replace the fuel filter and have good fuel pressure. After it hit temp it run grate I can shut it off when I get to work. At lunch it will start up fine and good all day. The mechanics looked at the plug and said they looked good.

 

 

 

Hope you can help me out. Thank you