Had a power issue this weekend

OK, 95 ZJ, 160k miles, 4.0. Took it upstate NY this weekend and it seemed to be struggling just a bit on the hiway. I could still maintain 65-70 but inclines were starting to be a problem. When I got up into the mountains it was a nightmare. The last large/long hill before my house had me down to 35 mph. Normally I can maintain the speed limit no problem even though the 4.0 is no race car. It downshifted to 2nd and 35 was the best it would do, if you floored it, it would just sputter, about half throttle was all you could do. When I got to the house I opened the hood to look for anything obvious. Only thing I could find was 3 of the spark plug wires were not securely pushed onto the dist cap. I firmly seated them then pulled the plugs in case one or more had fouled. Plugs seemed fine, no carbon buildup, more that whitish gray color. I have a plug cleaner for my snow mobile so I ran them through that but it didn't seem to help much. Tune up less than 12k miles ago and it included plugs, cap, wires, fuel filter, air filter etc. Any thoughts or ideas??? Catalytic converter? Exhaust seemed a little noisy also? Related? Thx Cory

Had a power issue this weekend