I had a similar problem with my Dakota (although, lucky for me, it didn't happen while driving, it happened, I'm guessing, upon start-up).
Heres what to do:
Get a helper. Temporarily remove/relocate the distributor cap (there shouldn't really be a need to remove any of the wires, just a few at the most if you do). While looking at the distribtor rotor, have the helper crank the engine, it will only need to be cranked for like half a second. The rotor should move (spin).
If the rotor DOES move, disregard the rest of this post and just post back that the rotor did move
If the rotor DOES NOT move, than remove the distributor. Find a place to relocate the camshaft sensor (I tucked it behind a wire bundle). On the passenger side, there is a 1/2" bolt that holds the distributor in place. It's tricky to remove, and kinda hard to get to thanks to the oil pressure sending unit. After that bolt is removed and the hold-down plate and distributor assembly is removed, look down in there andthere is something else to remove (my grandpa did all the work while I watched, so sorry I can't give a better description). He used a magnet to remove it.
Now, you need to get your friend to crank the engine.(I did this manually
, using a socket [forgot the size] and ratchet which goes on the crankshaft damper at the front of the engine, and that's exactly how I would recommend you do it, too). If, when your friend "cranks" the engine, and you don't see anything moving in the hole the distributor once was, your looking at a broken timing chain. Otherwise, if you see stuff moving, something with the distribuor drive is messed up.
To remove/replace the timing chain you have to remove a few things on the front of the motor (temporarily relocate the generator and A/C, remove the water pump, etc. etc). So, if your water pump isn't brand new
, since you have to take it off anyways, now is a VERY good time to replace it and ALL of the hoses (heater hoses and the short bypass hose at the top of the water pump included).
Also look into getting a better timing chain (double roller). I'm not going to act like I know whats better about them, but everyone I talked to said to upgrade to one.