89 3500 454 acts like loading up

89 3500 4x4 454 just bought it today. has headers dual cats and glass packs.apparently they didnt put the o/2 sensor back in cause i see the wire and showing o/2 code. taking off it acts like its loading up till you stomp right on it.going down the road at 55 does it until you kick in passing gear then it smooths out for awhile. i'm gonna do a tune up this week and i have to change the trans cause it junk so i'll weld o/2 sensor bung in then. just wodering if you guys thought i was on the right track. thanx oh truck is tbi in case you wondered.

Start by adding the O2 sensors back in the system.