Nezinscot

My '98 starts up - runs fine for 5 to 10 min idling or going down the road for several miles. Then it starts running very rough. Stop, pull over, rev it up, then go - but it still runs rough but you can keep it going. When you put a load on it, starts coughing and spitting. Don't dare drive it more than a few miles from home.
Originally put dry gas in. Took to service station, they put in a crank sensor - said no codes showed, up even while running rough. Fuel pressure is good. Changed the ASD relay, didn't make any difference.
Any ideas? Been trying to figure this out for months. Thank you.