As above...If runs on starting fluid it is fuel problem but maybe not fuel system.
You have spark so forget pip.
Yiu can unplug it to test and the distributor will now be self contained and not computer controlled but will be about 10 degrees advanced.
It could be connection from computer to injectors.
If all was well before water spray look for any and all connectors and one at a time open each one and blow out with compressed air.
Look for fuel injectors and follow the harness to get any connections cleaned.
Our van has issue that stranded us and solution was to unscrew the connector and wiggle it on and off a couple times then repeat and secure the screw so try that.
The pressure may be there but too low to work and the is a roll over switch but yiu state it stays running so tank unit working so switch goid.
Cannot remember if secondary pump...Ours is 89 too but have not messed with it in years.
Do get a Haynes manual as they are great for issues like this too.
Tony & Lori
1989 Country Coach Savannah SE