1999 Caravan 3

Normal idle with foot off gas, in park, the engine idle is 1500 RPM engine runs smooth no rough idle no codes now. Had code P1294 target idle not reached cleared code did not retrun. Other then the high engine idle in park no other issues. Replace IAC TPS PCM spark plugs sparkl plug wires coil pack completely clean TB

Yes, no sounds of a large leak, no air lines unpluged - checked all air lines around engine surge solenoid and EGR also cleaned EGR unit and underneath vehicle lines leading to canister visual only no cracks or bad areas. Sprayed TB cleaner and noticed a very very slight change in RPM response on intake manifold on corner area around spark plug 6 outer edge of manifold, checked torque on bolts of manifold in that area ok - could be air leak - but at this point unless there more evidence of a leaky gasket won't change out - Is there a method to check for air leaks with auto vacuum gauge, have hand held unit Also just noticed on cold mornings now there a rough engine start for about 60 seconds RPM 700 - 900 surges RPM up and down - then engine warms up ant holds at steady 1500 RPM in park and 1000 RPM in drive