I wish i could give some insight into the back pressure but that might be symptomatic of something else. It,s definitely too soon to replace the o2 sensors.
As for the island.... Yo encanto!! I moved here with the wife and and gained 30 lbs. Got that in check now. There is everywhere to wheel here, Jeeps are king here plus they love the old samurai,s. People vacation here but never get past the resorts. This place is all mountains and beaches built for Jeeps. We recently set a record for the biggest Jeep get together. If i find it i,ll post a link but it,s probably en espanol lol, where did you live here?