"Hesitation" or...a "jerking" feeling, acceleration

Hi~
Obviously new here, and trying desperately to find out what could be the problem before taking my 1300 mile journey, moving out of state on Monday!

I have a '99 Gr. Cherokee Laredo, bought it used two years ago and have had no problems, of course, until this past week. Now, it feels as if it is hestating, or jumping...almost a jerky feeling, when I hit the highway, and accelerate. When I coast, it seems fine.

I took it in to Merchants yesterday, and of course, he couldnt feel anything wrong on the back roads, and the computer did not indicate anything specific. But, while it seemed more or less "better" this morning (I had put some STP gas treatment in yesterday), it feels crappy again this evening. I just dont want it to leave me and the kids stranded on 95 next week!

Any thoughts? :uhoh:

Thanks!
MCD

Having similar problems and have had several suggestions.....one is replacing the fuel pump.....one is the crank position sensor....