Yeah, before they started fooling around with gas filler tubes, this was a common occurrence, But with limited emission controls, all cast iron, a flush or even thinning it out was all they war needed. Ha, still ran, but left a trail of smoke.
With fuel evaporative emission requirements, fuel injectors, a far more major job, but so is AC work when they dumped R-12 in favor of R-134a. Damage to the O2 sensors can result and definitely the catalytic converter.
But having problems with engine damage, much can be cleaned up with Seafoam, not really not much different than having fouled spark plugs, the engine just quits running. Diesel should not hurt the fuel pump, ethanol does a lot more damage than this.
Really can't help you unless I look at the engine. But is one hail of a big mess to clean up. Problems around here is not diesel but water in the gas.