I have a very...intense problems with my 2006 Wrangler. It's a six speed manual, 2.4L.
First, one some days, it will begin surging (almost a start/stop action), as in too much power then not enough every 10 mph unless I immediately shift up. This causes issues going uphill, because the Jeep will want to be in a higher gear than can give it power, so it loses speed until I have to downshift, which immediately leads to the surging.
The second part of this problem is that at 60 mph, it immediately loses power until the speedometer falls to about 54, then it begins to respond again.
As you can imagine, this causes some issues on the highway. I've tried to google the problem (and always get a lot of Toyota pages) but I'm having a hard time narrowing it down. Has anyone experienced something like this?