misfire #1 cylinder

Loses compression

no top end noise. no overheating

Perform cylinder leak-down test with engine at operating temperature to confirm 'where' compression is being lost... It's either blowing buy the exhaust valve .. The intake valve or the piston... Have got to know that before an effective repair can be made! .. IF not equipped to do the testing, see answer # 1 .. Looks like that shop is close by.

we would be glad to diagnose this issue for you just let us know it does sound like its leaking by somewhere