I have a 1999 that's loosing power when we first start driving it. Then after about 5 min it runs fine. It starts fine yet within the first five min the RPM's will go as 500 to 1000. It will do that for about a sec then come back to full power. Today it completely stalled out. Once I got it stoped and in park, I started it up with no issues.

I thought it was bad gas yet this has been going on for about 4 months. I changed the fuel filter yet no changed. Ran Lucas carb and injector cleaner through it yet no change. Here's some thoughts I have been told:

1. Change the mass flow sensor
2. Change the fuel pump
3. Change the fuel module

Before I start changing parts I would like to diagnose or test parts as much as possible. Know what I mean. So if you have some ideas, I would appreciate it.

 

Start by carefully cleaning the Tthrottle body and idle air bleed passages behind the throttle plate. If the passages get dirty (common issue) it can cause the issue you are describing. It may also be the IACV (intake air control vale) on the back of the Intake Manifold. It could be dirty or just defective as well.

Hope this points you in the right direction.. !

 

Good thoughts, yet if it's dirty wouldn't it keep dying out on me as I drive and not just within the first 5 min?