Nissan Repair: 01 Xterra, nissan dealership, nissan dealer

Question
When I get fuel and drive a couple miles, it jerks and acts like it will stall. It usually runs fine after using a bottle of water treatment until getting gas again. I found if I don’t go under ¼ tank or don’t pump gas in fast, I don’t usually have the problem.  Gas was a muddy gray color 3 weeks ago so they "treated" the gas for water and replaced the fuel filter the second time in the past year. I used regular gas until 3 weeks ago and since have used medium or high grade gas per repairman’s suggestion.  I got gas Friday, stopped at two stores within a couple miles. It stalled (this is new) after driving a few yards in the second parking lot, then it would stall every few feet. No lights come on the dash. It stalled once during repairman's test drive. He let it idle awhile and it misfired and skipped several times.  He said the computer did not pick up anything since dash lights are not coming on for a problem. Said fuel filter and spark plugs look fine. He replaced the distributor and kept my old one to put back on if it didn't resolve the problem. I had the skipping problem again after just driving a few miles. There were strong gas fumes behind it after it stalled and after the last skipping incident. Could it be the catalytic converter or trash/water in the gas tank. Would this be better handled by a Nissan dealership?  I was to have left yesterday for a trip - 600 miles one way but do not trust it to leave town. Please help!  Thank you!

Answer
Yes, a Nissan dealership would be your best bet. I know that there is a campaign for a new fuel sender for your model, however it may have been replaced already. Call your local Nissan dealer, and with your VIN number for your vehicle they should be able to tell you if your vehicle needs this campaign completed. If it has already been completed I still suggest taking it to Nissan