Oh joy, I'm back.... additional info

[Roa, Greg]

Oh, a few other things I forgot.
Car has a new idle/wot switch, new fuel pump, and new battery.
I've also run codes, comes back 4444 every time.
Engine stumbles when the dipstick is removed, and stalls when the oil cap is removed.

Only other puzzling thing I've noticed is that the gas tank seems to be pressurized when I open the cap after the car has been running.  Hear a whoosh, and air rushes out.

Thanks!
Greg Roa
Cincinnati, OH
86' 4kcsq x2
87' 5kcstq
93' 90CS
83' 944