Please give me advice!
Vehicle:
2008 Chrysler Town and Country, 3.8L
Current Codes Reading:
PO303 (cylinder 3 misfire), PO300, PO301, P1404 (EGR Close Position Performance), P0201 (Injector Circuit Cylinder 1 Open)
Current Van Behavior:
Check engine light came on and it was a random misfire, but no sign during running. Then the van began shuddering around 40-60 mph if I drove a second time AFTER the engine was warm. I could drive forever if it was the first time, but once I turned the engine off and restarted it, van would ride rough. I then changed the plugs and wires to no effect. I am almost certain it is electrical, as it seems to be worse when it is wet out. I have noticed in the last couple days, I have airlock in the radiator, with a cold cap, but the engine does NOT seem to overheat. I do seem to be losing some coolant. Now the van runs rough all of the time, whether it is the first start or not. It shudders and seems to lose horsepower. The water pump went out last year, but I replaced it and it drove 5000+ miles with no signs of issues.

Next Steps:
I may change the EGR Valve or the Speed Sensors on the tranny. What should I test? Where should I look?

Other information:
Randomly the radio will turn off and back on while driving. I have damaged the sliding door wiring harness on the passenger sliding door. Some of the wires are broken.

Thank you for your time!

 

Alternator issues, just had the same thing (Radio thing) on my 3.3, once the alternator was replaced (the bearings failed on it, had been going before), the radio stopped turning off and on, there was lots of odd little electrical issues before as well, so could explain what you are having.

I would check the alternator out.

Check the core plugs/freeze plugs, at the bottom of the block, could be a small bit of corrosion letting out a small amount of coolant, quite common.