Nanks, we are all sort of flying blind here. What size tyres do you currently have on it?? I can't see anywhere that you have mentioned it. Are they stock, 31's, 33's????
I have a 96 cherokee. I realise it is not a TJ but it still has the 4.0 ltr straight six. It has approx 260,000kms running custom extractors through to a 2.5inch system. It's an auto and I run 31 inch muddies (standard gears) and tow a Trackabout camper fully loaded. I travel at 100-110km/h on the highway and only need to drop back to 3rd on hills with the trailer behind me or when over taking. Even then, the torque converter kicks in and drops the revs. For an older motor, still has a heap of balls. It has also done a shit load of towing between Brisbane and Sydney up and down both the old and new highways with boats and trailers etc behind it in it's younger years.
I have had it for 9 of it's 12 year life, and i suppose only now am i starting to see it getting a bit tired. Still not a puff of smoke though.
So i think you may have an issue OR you are expecting too much from her.
Just a couple of questions.......Can i ask how tall you are???? Do your feet reach all the way to the pedals and can they push it all the way to the floor????
Sorry........Just kidding........
i still was able to put my right foot hard down on the floor 
