Durango shaking when on? why?

Why the dickens would you drive it after that happened?

Probably the syncros are going out, would have to get it rebuilt. Shaky isn't a word to describe a shift. If the car is shaking, it's not the transmission, it could be the transmission mount or motor mount.

Have a shop do the necessary testing, to find a problem

You don't change parts based on no testing & certainly
put no faith in autozone or anything free, is of no use to you

Hi,
What was serviced a few weeks back? Sounds like it needs a tune-up @ least to start - spark plugs, plug wires.

At 103K miles I'd also replace the fuel filter, air filter, PCV valve. And if you look in the Owner's Manual it should have a maintenance schedule for other items that may need attention.
GL,
TD

The check engine light flashing is a pretty much universal sign that you have a misfire that is bad enough that a lot of raw, unburned fuel is being dumped in to the Catalytic Converter, to the point that it could be ruined if the problem is not taken care of very quickly.

it sounds to me that #7 has a valve train problem, wiped cam to broken rocker arm,bent pushrod,broken spring,bent valve or burnt bad! Or it has broken ring on piston. shouldnt have kept driving,very bad idea. pull valve cover to check valve train. I would start there before going deeper into motor.

Check your fuel pump which is located at the top of the fuel tank. Dismantle and check the "o" ring which may have disintigrated if you are using Gasahol

a flashing check engine light means catalyst damaging misfire which is just about the worst thing for your engine. i suggest not driving it til its fixed. misfires will cause it to shake. check for spark first.

Very possibly you have a bad motor mount. Is the engine missing or running smooth but shaky? If it is missing, then it may be plugs, wires, or injectors, if runs fine but shaky, then you may have a bad motor mount.

This sounds like coolant hose blew. Check all. If you don't find it, fill the rad. If no leak shows up, replace the rad cap and start it. Sometimes it has to build up a bit of pressure. When you find the hose, replace it and any others that look iffy with New hoses! Do Not Cut Corners!! Frankster016