Have 93 Explorer with 160k on rig. Been a great rig but now has lack of power\hesitation problem when out on highway, and accelerating to pass or climb hill. Seems to only occur, when RPM around 1800-2000.
Occasionally will even backfire. Once auto trans downshifts out of
OD acceration seems fine. Can O2 sensors cause this? Don't get a check engine light, Plugs and wires recently changed with air and fuel filter. O2 sensors never been changed. Is their a way to check them, 4.0l takes two of them and they seem expensive to swap out if unneeded. Thanks for any help.

1993 Explorer XLT
4.0, auto
all else stock

 

thats funny that you ask this, im getting a bit more hesitation then usual when im going uphill or down the highway in my '91... no backfiring though (lucky me)... I've gotten some various responses from my friends, one said the transmission is going (i doubt that), another suggested the same as you, the O2 filters... maybe someone else around here knows a bit more?