P0300 cylinder 1 failing running compression test
 

I have a 1998 C5 corvette with 93,500 miles on it I haven’t put hardly any miles on it in the last two+ years since I haven’t driven it for at least one year without touching it. It is now having problems.
went through all the easy fixes and ruled out electrical issues without correcting the problem and took it it to a professional shop that I have dealt with before and respect their skill and integrity. Shop said it was definitely a mechanical issue, cylinder one is not holding air pressure I Verified this by applying air pressure to the #1 cylinder and it failed to hold any air pressure I’m looking at pulling at least the heads possibly the motor was advised to put transmission oil into the cylinder and watch for the level to drop to determine if my problem also included the piston rings.
Any suggestions before I start pulling the intake and heads off?

Welcome to the forum. I would pull the #1 spark plug and connect an air compressor to it so that you can remove the valve springs and see if you can feel the valve seating when it's closed. It could be something as simple as a piece of carbon on the valve seat preventing it from fully closing.

Next I would run a pressure test on the cooling system to rule out a cracked head or block.

Finally I would pull the head and barring seeing anything obvious, I would drop the pan and pull the #1 piston to see if it's the rings.

Welcome to the forums. The shop guys should have told you where the air blowing into the cylinder was going to, if they went that far it would have taken a few minutes to trace the sound.