can it be the catalytics? i hav lo power in the 2-3k revs

 

Both symptoms are indicative of a bad cat(s). So, yeah - catalytics.

 

then i guess il just do a de-cat

 

Removing the cat is ill-advised. The car's computer controls the ignition and fuel delivery using feedback from the O2-sensors and, therefore, factoring in the catalytic converter. It won't run right without a cat - you'll at least need a professional tune.

A proper cat doesn't hinder exhaust much, so deleting it won't gain you anything. Overall, just replacing it is the best fix.