My bet is either a clogged fuel filter or a failing fuel pump. Your description has classic symptoms of fuel starvation. A clogged filter or weak pump will let just enough gas thru to idle or run at low speed, but at highway speed or especially under heavy acceleration it can't get enough fuel.
Checking fuel pressure at the injector manifold is fairly easy for any mechanic. Cost to replace the filter is minimal for most cars; cost to replace the pump can be high if the fuel tank must be dropped (many cars have a fuel pump actually located inside the fuel tank).
https://www.yourmechanic.com/estimat...mp-replacement
https://repairpal.com/estimator/merc...placement-cost
http://www.fixya.com/search/p697307-...filter_located
Replacing the filter is easy enough you can probably do it yourself and the cost is minimal ($15-20):
https://itstillruns.com/how-to-repla...ars-10439.html
Best to do that first, THEN if it doesn't fix the problem, take more steps. Don't let them talk you into the expensive fix first.
Well, I did pay a $100 dollar deductible for the shifter replacement (Jeep picked up the rest under the extended warranty). But of course, I had to buy the battery from Amazon, it being a super duper AGM battery locals wanted $230 for. but had I went back, I would have had the $100 copay, and if they had found the battery, I would have been on the hook for their overpriced version, well over $200 which I know only lasts two years :) But I'll bet they would have kept throwing other parts at it, computers, modules, sensors, who knows. They don't troubleshoot, they swap parts. Anyone Gilligan trusts, I would two, knowing his chops.
"I aim to misbehave."
Try Marks automotive just south of PAX main gate. Incredibly knowledgeable, honest, speedy, and reasonably priced service. I have lived in somd for over 15 years and been their customer over 10. Truly the best in their craft in the area.