What would cause the switch to work opposite at times (ex. turning left blinker works on left) not all the time just here and there. Bad switch? Thanks for any advice!

I have seen this issue several times. It is usually the multi-function switch that is the problem.

Likely a faulty multifunction switch. Switch sends multiplexed signal to cluster, cluster sends bus message to FCM, FCM operates approiate lights.
Switch probably sending wrong voltage to cluster.

Gary.

For years I have not had a right trailer turn signal/brake light so I was told it was the FCM. I replaced the FCM a couple months ago and still have the issue, could it also be the multifunction switch and where the heck is it located?

If it is only the trailer portion that is inop then it wont be multi-switch (turn signal stalk).
Factory trailer tow harness? relay in IPM/FCM clicks?
Need to review wiring diagram and check circuits with test light front to back.

Gary

Is the switch that hard to change replace or need special tools? Wondering if Ishould let the dealer fix...

It is easy to replace. Just remove the upper and lower plastic steering column covers behind the steering wheel. The screws come in from the bottom of the lower cover. After you get that off just remove the 2 screws holding it to the column and electrical connector. Then grab the handle and pull it straight out of the bracket. FWIW, a Mopar switch will come with the bracket on the switch. Just remove the switch from the bracket and install. Otherwise the steering wheel will have to come off to replace the bracket, resulting in much more unnecessary work. One more thing, Dodge put an extended warranty on the switches for the 06 Rams. This switch will also fit your truck. It can be had for somewhere around half the price as the one they will try to sell you at the dealer for your truck. Just ask for part number CNH3X2DDAA.