1998 Caravan SE 3.3ltr studdering problem

I have a few questions regarding my 1998 Caravan. It's a 3.3ltr with 170,000 miles on it. She runs like a champ but has developed over the last several months a "studder" when i press on the accelerator between 40-60mph.

I've replaced the plugs and wires as well as flushed the transmission fluid and replaced the transmission filter/gasket. It idols great now but the studdering issue is still there. It's not all the time but most of the time, I'm curious if anyone has any suggestions on what may be causing this issue.

This one is not as important but my interior lights no longer come on when any of the doors are opened. Only the front driver/passenger lights work if they are manually pressed. I've checked the relay's/breakers and all are good. Any thoughts on that?

***A side note is that this is a Braun modified EnterVan that has a fold out ramp and kneeling system so i don't want to mess to much with the electrical system.

Thanks
-Jim

My knee-jerk reaction is you have a fuel problem. My first course of action would be to replace the fuel filter and see if that helps. If that doesn't work, then I would have the fuel pressure checked at the engine side.

"Studder" = hesitation?

The possibilties list is long but, I would put the torque converter near the top. I certainly wouldn't change it as this point but, you might consider it if it gets worse. In the mean time, use nothing but ATF3 or 4 transmission fluid (check your manual) and keep it topped off. If it gets worse, watch for a Service Engine Light and have the codes read for free at Autozone.

Try pulling the IOD fuse for 30 seconds for your lights problem. It resets the body control module or BCM, which controls most of the electronics in the van. Big doubts but, worth a try. You could try reseating/tapping on/changing the courtesy lamp relay on the junction block under the dash (or is that the relay you checked). Next would be a headlamp switch. If you had a multimeter and know how, you could save some time and money.

A little irony. All my interior lights work except the forward upper map lights. I know it's the switch because if I wiggle it just right I can get them to blink.

I suspect your CAT converter is partially clooged if it is original.
My van had the same miles and same problem.
My CAT was clogged except for an area in the very center the size of a dime, causing too much back pressure.