Engine Performance problem
1999 Ford F150 V8 Four Wheel Drive Automatic 116000 miles
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ok i have a 99 f150 4x4 off road and it has 4 cats on it, my question is if i take 2 of them off will it affect my o2 sensors, reason asking is i took the one off my cousins 98 gmc 1500 and the diagnostic said it was running in "lean mode?", im doing custom exhaust work to my truck and i was wondering if you could tell me if i was going to run into the same problem.

Thanks
Pvt. Perry