Truck starts to vibrate, spits/sputters, engine light flashes. After a few seconds of this it clears up. Seems to do it on cold days after sitting for long periods. Had a sensor chip replaced 6 months ago when it was doing the exact same thing. Dodge dealer won't look that direction and is trying to find another fault for me to pay for.

A flashing check engine light means you have a catalyst damaging miss-fire. you will need to get the fault codes pulled so you can see what cylinder/cylinders are causing the problem. Once you have this information a diagnostic path can be determined.

check your fuel filter and pressure in fuel pump

I would first pop of fuel filters and check that rig may have only one but if I am not mistaken mine had one on firewall and one in line. both are like 15 dollars a piece try that first if not that then fuel pump. Another thing you could do is go to gas tank open then cap have someone turn on the ignition switch and listen you should hear the pump engage if not replace let me know if that helps but those are cheapest fixes I would start with first at shop

This can be caused by a problem in the fuel pressure check valve of the fuel pump. Have a pressure leak down test run by a shop, if the system is losing pressure then the pump assembly must be replaced. The fuel pump is located inside the gas tank and is electric

My first guess would be the O2 sensor. Low fuel pressure would cause the symptom but not go away on restart.

Have the shop check fuel pressure at the fuel rail. Maybe the pump impeller has failed. If fuel pressure is good, your timing chain/belt may have slipped.

You need to have the system scanned for fault codes.

sounds like a fuel pump problem,with fuel pumps u can have pressure but not enough volume,try goin up a steeper hill in 2nd gear and get about 3000 rpms on the engine and see if it really drops out bad and is really gutless,if that happens without a check engine light coming on it might be yur pump and u should also replace the fuel filter at the same time,hope this helps

first ... put a bottle or two of gas line antifreeze in the tank (it sucks up water in the fuel)... if that doesn't sort it out.... your coil pack may be dying

I recently had a similar problem. I got my car scanned and needed a new catalytic converter. If its already starting to spit and sputter, you probably have 3-6 months to get this done. Mine plugged up one day, and just flat out would not drive anymore. This cost of this repair was about (i recommend changing the spark plugs and wires also) $675....pretty costly. could get a lot more expensive the longer u let it go. Does your jetta run cold, in cold temp? (between 25-40 degrees) if so the thermostat probably took out the converter.