Engine lacks power at about 3500-4000 rpm..why?
 

i tryed serching but nothing. so yeah like the title sais i can feel the car loose power at about 3500-4000 rpm. how ever once it get to operating temp. everything is fine no more power lag. so i figured a dirty fuel filter. i dont know when it was last changed i had the car since july. i have also been hearing that it could be a ground isue but i dont see why it would go away when warmed up. so maybe some one here can help.

This sounds like the classic "3800 RPM Hesistation". Search with those terms, and you'll find a lot of info.

Also, just a thought, if you have a NA, there are aux throttle butterflies that close when the engine is cold to prevent it from being abused. If these are still working (rare, but possible), they could be related.

I'd tend to look at it being the 3800 RPM hesitation, though. 3800 RPM is where the secondary injectors come online and the primary injectors cut back to half their previous duty cycle, and grounding issues can make this a rough changeover.

-=Russ=-

so what i should do is clean the injectors and for grounding what do i ground...everything?