Rough Idle, Acceleration miss

[Railroader]

1996 Chevy Corsica Basic 3.1 150,000 miles
Vin: 1G1LD55M3TY272843

PO300 Random Misfire Code
Somewhat rough idle, engine hesitates, Misses, sputters, when Throttle opened fast

Here is what I have done so far.
Replaced Plug Wires
Replaced Plugs
Replaced Coolant Temp Sensor
Checked for Vacuum Leaks
Replaced PVC Valve Tube Assembly
Did Vacuum Test (15-hg Steady) (Snap throttle open test) go's to 5, 0, returns to 15-hg, (Deceleration: Goes to 25 or so then returns to 15 -hg
Replaced Fuel Filter
Replaced Fuel Pressure Regulator
Replaced Both Oxygen Sensors
2 Out of 3 Coils Replaced (did swap coils around, no change)
Checked Fuel Pump Pressure 38 to 40lbs

Things I have not done
Have not Checked Injectors
Have not done a close inspection to see if antifreeze is leaking around the intake manifold (Not readily apparent)
Have not checked EGR Valve (no codes)
Have not checked MAF Sensor (no codes)
Have not checked MAP sensor (no codes)
Thanks for any suggestions

[maxwedge]

See how it feels with the maf disconnected.

[Railroader]

It looks like the Intake Manifold is leaking, pool of antifreeze in the valley under the thermostat, and this is a known problem with the 3.1 engine. guess it is gasket change time. Did not appear to be any antifreeze getting into the oil though. Thanks

[Railroader]

That problems fixed, replaced intake manifold gaskets. Got another problem now.