engine wint rev above 3 grand
 

my 87 NA will start ok but if it revs above 2500 it will chug down again. im confirming my suspicions of it bieng the cat. im planning on having it cut out and welded, wil this affect my o2 sensor? adn im curious what i have to do to prevent any problems. because i don want my cats on anyway. and i want the extra power anyway. any tips or anything ? help soon would be great. its my daily. lol

Your auxilliary ports won't open. Your O2 sensor shouldn't be affected.

how is the exhaust flow from the mufflers? if its decent, your problem is not your cats.