Charles urs could be injector pump problems. Slow or no response is a fuel issue. I'm guessing y'all have changed the fuel filter.
Shotgun
Arkansas
Air,Mobil and file filters were changed before putting the new batteries in it. When the new batteries went in and ran fine then messed up again, is when I had the alt checked, and hung tested a new 1 and nothing changed. Which ruled out over/under voltage. All grounds are there, and even some new 1s I added. Now that judge mentioned the ecm, i will check all connections and run a new direct ground and try that. If that doesn't work, then I'll recomend him get a new ecm or vp pump.
Now he does have 25hp tuner on it, which may have something to do with it. I just thought of that. I'll check the connections and pull the tuner out and see if that fixes it.