2005 Dodge Caravan Check Engine light/Rough idling

Own 2005 Grand caravan (145K mi). Had check engine light, rough idling problem for month. Only occurs in the morning when van first started during 1st five minutes, when slowing down for stop sign/light or when it's first started in the afternoon. After 5-10 minutes, rough idling stops but check engine light stays on. If used later in day, check engine light stays off and no rough idling. Took to Dodge dealership. 1st diagnosis: lower intake caskets leaking and oil pan gasket leaking. They installed intake manifold gasket, installed seal for intake manifold and installed gasket for oil pan. Next day runs fine. 2 days later same problem check engine light/rough idling, took to same Dodge Dealership.2nd diagnosis injector connector #4 was loose, tightened it up. Next day, runs fine. 2 days later same problem: check/engine light/rough-idling. 3rd time took to local mechanic replaced spark plugs and wiring. Next day, runs fine, 2 days later same problem: check engine light/rough idling. Any suggestions as I'm probably going back to same local mechanic. Would like to give him a list of things to check on that could be causing this problem.