outofgas

Background:
Stock 1994 Dodge 1 ton Dully, 5.9 Cummins Diesel 2 wheel drive, automatic Transmission, Outside air temp = low to mid 90’s.
Thursday: drove about 50 miles stopped for about 1.5 hours while taking care of business. Was on my way home (30 miles driven) when I had to merge from one highway to another on a very short on ramp. So I gave the beast full throttle, the turbo kicked in and off we went for a beautiful merge. Before I realized it I was doing about 90 mph and backed off so that I could slow down to 65. The truck began shuddering and at first I thought I had a flat but there was nothing wrong with steering or shaking in the steering wheel. My next thought was a motor mount or a u-joint. So I slowed down and after about 5 miles pulled into a gas station. The engine died as I slowed down to make the turn but restarted fine. I went in and got a soft drink came back out and inspected the tires, ok; raised the hood, engine still there and no visible leaks or damage. I got back in started the engine and drove home at 60 mph (15 miles) without trouble. Later that day I drove about 9 miles to Lowe’s and back without problems.
Saturday: Drove 65 miles to a Flea market and spent about 2 hours browsing. Got in truck and headed home when about halfway the shuddering started again (speed was about 60 mph). This time I watched all my gauges. Oil pressure about 42 psi, volt meter 15, Water Temp 190° RPM steady at about 1800. I slowed down to about 55 MPH and continued home. Again when I slowed down for stop signs the engine died once the RPM dropped below 800 to 900, this happened 3 times in 25 miles (every time I had to stop).
Got home shut engine off. Placed it in park, started the engine and let it idle (idle is about 600 RPM by factory tachometer. Engine sounded a bit off but idled ok. Note I’m 69 and wear hearing aids so my opinion of sounded ok may be a bit off.

I am fairly sure it’s a fuel problem, air, leak, low pressure but would appreciate some feed back suggestions or advice before I begin testing everything. Fuel filter was changed about 8,000 miles ago (but that’s been almost 2 years).

I am a reasonably good mechanic but just getting the time to explore my diesel now that I’m retired and have the time, in short not completely ignorant but in need of help.
Apologize for the long post but wanted to give enough information.

Additional Info: While checking engine compartment with good light source I discovered that the positive lead from my second battery was very loose. I just replaced both batteries not long ago. Fixed that problem and did not see anything else. Drove truck about 10 miles with AC on high and at road speed and it ran very nice. I need to do a longer run probably and continue checking for any fuel problems but????