Hey there Lpjackson,
What is the p430 code for? As far as transmission fluid goes; There is a difference between having it changed and having it FLUSHED. If the fluid and filter have never been changed to your knowledge, I think it would be a good idea to get those changed. If you take it to a shop, just tell them that you want the fluid and filter changed and not flushed. Also, while you're at it, you may want to go ahead and tell them to go ahead and change all of your fluids since its already in the shop. That should cover coolant, oil/filter, trans fluid/filter, wiper fluid, etc. Also, you may want to see how much they'll charge to replace your fuel filter as well.
I'm not very familiar with the fuel pump setup on your GC, but I know for a fact that on my ZJ, a clogged fuel filter can definitely cause some intermittent jerking/sputtering issues; especially when accelerating. I replaced my fuel pump and filter a week ago today, and the filter was absolutely disgusting. Believe it or not, my Jeep doesn't have very many more miles on it than yours.
I was actually having very similar issues with my '98 Grand Cherokee this past week. Not only was I having some sputtering and jerking, but sometimes my Jeep would actually stall at idle and even while driving at 50~ mph. I ended up replacing my Throttle Position Sensor, Ignition Coil (My ignition system is very different from yours.), and the Fuel Pump/filter. I think my main issue was the Throttle Position Sensor, but all of the other parts needed to be replaced anyways.
If you can tell me what exactly the p430 code relates to, I can probably help you pinpoint whats causing your driveablility issues. If not, I can at least help you narrow it down.
I can imagine all of this is probably overwhelming, but don't be discouraged. Jeeps will last you a long time as long as they're properly maintained. At 150,000 miles, a little extra maintenance is to be expected. But don't worry, we'll figure this out and hopefully you'll be getting at least another 150,000 more.