Chevy & GMC Vans

Hi all! I have been silently reading this site for its valuable insight.
Above the technical knowledge I've gained, I've learned that people love these vans!
I love my 94 decommissioned power company van with added tool shelves and ladder rack.
As a fleet vehicle, it was taken care of for 186,000mi. I've added another 30,000 in 6 years with regular upkeep...
Van running fine, but failed emissions. New plugs, wires, cap, rotor, coil, PVC, IAC, TPS, MAP, purge solenoid, most vac hoses...
(I know this may not be the right forum, but I'll get to the exhaust soon)
Fuel metering and timing seemed to be the corrective trail I was perusing.
I opened the plenum and thoroughly cleaned my CMFI spider and the sludge filled manifold halves.
MUCH more power, but unsteady at partial pedal.?
So I mess with the timing in both directions for a couple of days, and then suddenly she's cooking me without the Dog House.
Benn running @190F, but was soaring to 240+ at stop lights.
(Here Comes The Bad News):
The next morning after threatening to boil over, she pluming white smoke, spitting rusty water from the tail pipe and worst of all, water is pouring
out of my Cat and from the donuts under each exhaust manifold!!!!!
Somebody tell me this is not what I think this is!!!!!!!!!!! HG?

Best case-Blow intake manifold gasket,head gasket,worst case,cracked head or warped head,cracked block.Now we could talk about a number of tests to find which is what,but at the end of the day,it's got to come apart to really know.

Thanks Gary. I was afraid of that. I am hoping it might be just be lower intake gaskets. I have oily paper shreds in my coolant overflow, but no water on the dipstick.
Post mortem exploratory surgery it is.

There is nothing wrong with a progressive tear-down starting with the lower intake gasket and inspection.You would have to take that off anyhow to if need be look at the other stuff.