Car is a 1997 GT with a L67 Motor. Car had a vacuum leak LTFT's were at 16.4 sprayed starter fluid around found the vacuum leak was from the EGR tube in the LIM. Made block off plate from aluminum, put it on LIM. Disabled the EGR in the PCM. Start the car...all seems fine, heats up to temp then starts chuging, I'm watching the laptop (powertuner) o2s would be jumping around while it was fine. Then after a few more seconds the o2s from to 60..50...40...30...21.7 then STAY at 21.7 and car chuggs. Hit the gas onces o2s start jumping around again...then after 1-2min chugs again. Also when it starts chuging the LTFT's go from +10-12 to -10 and richer the LTFT's get the harder it chugs. Does this have something to do with open closed loop? What's messed up need help ASAP!