1995 Pontiac Bonneville no start

Pcm had codes p0341, p0342, p0705. Changed cam sensor. Engine has spark from coils, injectors are
pulsing, fuel pressure is around 40 psi. The motor is a 3.8L series 2. Just replaced intake plenum about a
week ago. Intake and cylinders were filled with
coolant causing engine to be locked down. Ran fine
for a couple of days. Went to crank it would turn
over but would not start. It has not started since. I
replaced spark plugs when I changed the plenum. I have tried everything so I pulled the plugs this moring
just to have a look. They were soaked with gas.
pulled the oil dipstick. It wasn't overfull but smelled like gas. Any ideas what my problem could be.