This is advice for you doors only not tailgate. Buy graphite spray lube, not silicon, not oily, not PB.
For doors suck it up and remove the inside panels including speakers. It's not as bad as it sounds. Just remember where everything goes. Then you will see everything and how it relates--play with it. I don't know the names of any moving door parts. This way you can eyeball what part is not working. I've done this before and didn't need to buy anything. I had to straighten a rod with a pliers, and spray the crap out of "tired" parts...including lock cylinders, arms, etc. You need a weekend afternoon. Not difficult just some hours on the clock.