2.4L CIS running rough & missing
 

My 2.4l CIS has been in storage for about 4 months over the summer. Before storage it ran great, but once started after storage, it was hard to start and took longer than normal to get running and up to idle. It now runs rough and misses, although it has all of its power. Any suggestions as to what might have changed over storage and diagnosis? Thanks - Mike

Could be just an old fuel problem. Did you use an gasoline additive/preservative before storage?
Last time filter/accumulator replaced? Replace or use up the remaining gas that’s in the tank though 4 months might not be that long for gas to go stale and collect moisture depending on your climate conditions, take a look under the distributor cap and check for moisture too.
Many chance mice may have nested and nibbled a vacuum line?
Finicky CIS problem also which I found with mine on cold up though mostly after long periods of not driving, I have worn valve guides so plenty of smoke and and over rich mixture.
Plenty info available to troubleshoot but your situation should start with some of the basic easy stuff since the problem began after the storage period.

Do a basic tuneup: plugs, filters, timing and, if needed dwell. Then run a tank of non ethanol fuel with Techron for a long hard drive. See if it clears up.

Then look for more complicated things.

Drain the gas using the fuel pump and some extra hose. Start with fresh gas, pull your plugs clean or replace if they don’t look good. If it’s still not running right check fuel pressures and ignition system