Is the miss there all the time? Have you had a vacuum gauge on it? Been burnt before checking for cyiinder leakage with shop (90 + psi)air pressure. Sometimes a valve will show a leak using lower air pressure. We have a EVAP tester at the shop that I have used to put smoke & nitrogen into the spark plug hole & watch the smoke come out past a valve that "didn't leak".
Running compression test another thing that might help.
