We have a 97 Caravan 3.0 that runs great as long as you are not taking a trip over approx 200-300 miles. The van runs good then all of a sudden it will just lose power and quit, (sometime it will just idle) if it does quit running, it will not restart. After the van "sit's" a while it will crank back up ( sometimes after 2-3 minutes sometime after 10 minutes and one time it would not start back up for a half hour ) and then it runs like nothing happened, it seems to do this more if you are running over 70mph, and the only "common time" for it to happen is on a long hwy trips, we run the van all over locally and it never has any trouble.
And the van does NOT throw any codes when this happens.
The other wierd thing our van does is while driving down the road the speedo will "drop / bounce" down then up and resume working normally. This also happens at completely random times. When it does this the motor seems to miss just a little bit. Running diagnostics on the dash AND the PCM is not showing anything wrong.?
The van has 168,000 miles timing belt was changed a few years back when the water pump went, just replaced the fuel filter suspecting this was the problem but it did not correct the problem.
Any ideas why these things are happening,