Lowspeed loss of power and then backfires.

Problem: 96xj with 176k on the ticker. 4.0L. Lately this problem has been occurring more and more often...it seems to happen after I've driven for about 5 miles, and then let it sit for 5-30 minutes. I'll get back in, start it, drive off and if it gets to about 1500-2000rpm in 1st gear it'll bog down a little. If I give it a little more gas it'll backfire and then all will be well and the torque will return. Got any ideas? I'm guessing either o2 or TPS. Also, after it has cooled down and sat for a while, and I start it to take off, it doesn't run quite right. It'll idle fine, but if I rev the gas it sounds rough and misses.

Loose honey comb in the cat converter, or loose baffle plates in the muffler restricting the exhaust (they can come and go for a while), or the TPS is going bad would be my first to choices.