Caravan, 3.0 L, engine misfire

You need to perform a compression test, If it is low you can try to decarbonize the combustion system with a product that Chrysler sells, Make sure you are using 87 octane fuel also. Glenn Beasley Chrysler Tech

Also possible you've got a worn or loose valve guide. Problem is not as common as in the past, but apparently it still happens.

Kind of what Max power said...do a compresion test. Now, if the compression is low then you would have to do a wet test, meaning that you squirt some oil into the combustion chamber and check the compresion again. if the pressure is higher then that means you have bad piston rings, but if the pressure doesn't change than maybe perhaps your valves are bad. Worst case scenario: engine overhaul.....very costly and depending on how you feel about it if you think it's worth it then go for it, but if not then its just one of those things that u learn to live with.

Garage had done the compression test and it was fine.

Any chance it could be a bad injector? What about the fuel filter, could that cause it?

The guides in my 88 NewYorker were so bad it's a wonder the valves didn't come up through the guides, and the compression still checked out fine - but it didn't run worth a hill of beans, and used a lot of oil (and did not smoke)

Those Mitsi engines wear the guides real bad. New guides and a valve job is a must after about 100k miles. problem used to be worse but they have improved the heads and they are better now.