Pull the codes first and if you have to remove the Cat spray the bolts with PB Blaster, their's no need to grind anything. The Os sensor is not in the loop while warming-up. You problem could be a number of items, TPS, fuel pressure reg, dirty injectors, et... Pull the codes first.

1989 Toyota SR5 DLX SB
1995 Toy DX XTRA Cab 4x4
1989 Dodge Raider 3.0 V6, 5 spd, Michelin LTX series, bouncey seat
1988 Dodge Raider A/T w/Offroad Package
1959 Corvette
1977 Z28
1979 Honda CBX 1000 6 cyl