96, GC, 4.0. 264K miles. Started throwing a P0420 when traveling at crawl speeds or if I lit it sit idling to warm up for say 10 mins. Can drive it 500 miles on the highway and no P0420 (Cat at 95% of normal ops IIRC). Old fuel pump was noisy and figured its on its way out. PO gave me a new in the box pump (Oreileys brand) so I installed it. New one is just as loud, and now some 100 miles later, if that, in getting a p0171 code. Lean condition. Both 02 sensors are originals far as I know. Opinions on the likely hood of the 02 sensor(s) being the issue? Runs as normal, fired right up with a second of hitting the key as well. TIA, before I take this think to the junk yard. I have noticed however this forum is almost as worthless as a jeep GC.