The same thing happened to me and my truck. 1996 ext cab diesel. about 3/4 gas added maybe a little less gas...
Anyway, when I got a few miles down the Interstate, it sounded and started driving different.
I slowed down (as it wasn't doing anything scary) to 55mph, and just lightly used go pedal. Next exit with diesel was about 40 miles down the road, and I added 2 gallons diesel there. Another 40-50 miles and 2 more gallons added. Kept doing this until I got back home (approx 500 miles later). Drove it carefully from then on until tank at 1/4 full, filled it full w diesel, and forgot about it.
All good. That was in 2002, about 250,000 miles ago. 451,000+ on it now. Just rebuilt (with uprated mainshaft, bearing upgrades etc, and a 6 speed flywheel and clutch component kit (sachs), starter brush upgrade (Cummins non cut down brushes), new A/C cab to compressor, and KYB shocks. By the way, the best upgrade besides tst #3 plate and 270+ rwhp/840 rwtq were those shocke! I had already put Gabriel HD high performance shocks on it in 2001, at 230,000 miles, but WOW! The kybs changed the truck steering, ride, handling, EVERYTHING is so much better. They are expensive (for shocks) but best upgrade for $ I have done on the truck, and any vehicle, I owned.