hesitation at 2500

looking for a little advice. i have a 91 gts almost all stock 5 speed. the only thing that has been done is a cone airfilter (not sure what brand) and aftermarket muffler. both on the car when i bought it. latley it seems that between 2500 - 3000 rpm i feels like some one is pinching the fule line and the car has no GO. you can feel it more when the car just gets started and after about 3 minuits of driving it isnt so noticable but it is there. i have just changed the spark plugs and that didnt help, even though the old plugs were trashed. my next thing i am going to do this weakend is get the multimeter out and check the MAF sensor. does anyone have any other sujestions as to what else might cause a problem over such a limited rpm range?

My suggestion to you is ask on another site cuz you'll be hard pressed to get an answer from this one. Check to see if your MAF is dirty if so spray it and the connection down with electronic cleaner. Let it evaporate then hook it up and go for a spin to see if it helped. I've been having the same problem with my R. I narrowed it down to either needing 2 new MAF's from a 300 or a new fuel pump and or filter. Hopefully cleaning does the trick for you. Post back and let us know what happened.

I would say MAF sensor as well, cone filters can cause oil to get blown over your MAF wires causing hesitation as boost builds up - your 2500 to 3000rpm range!
Clean the MAF sensor as previously stated. Cleaning your air filter is a good bet too, too much dirt could be restricting flow

just cleaned the airfilter 100k ago with the sparkplugs, but ill clean the maf in a bit. weather has'nt been verry nice today. btw it's a non turbo car, but i dont think that makes a difference.

Non-turbo huh... That is weird...
Try your PCV breather, it is the hose that connects from your inlet cam cover to the inlet manifold. The PCV screws into your inlet manifold, the get blocked up with grit and sh!t and are known to make the car loose power, cleaning it out with a can of throttle body cleaner would be a good idea.

Removing your intake piping and spraying some throttle body cleaner on your throttle body and Idle Control Valve would be a great idea also!

Try your PCV breather, it is the hose that connects from your inlet cam cover to the inlet manifold. The PCV screws into your inlet manifold, the get blocked up with grit and sh!t and are known to make the car loose power, cleaning it out with a can of throttle body cleaner would be a good idea

you think that might cause a problem under a limited rpm range? i'll give it a try and see what happens.