Yes, the throttle body could well be shot.

Exact same thing happened to mine.

Before I got the lightning bolt, it felt like the transmission was slipping, there were no codes that my scangauge or older actron reader could see.

But I purchased a different scanner that gave me a code for ice blockage in the throttle body. This code doesn't set any error lights or trigger limp mode, at least in my case.

 

For reference, here's the manual info:

 

Thanks! That's a good thought -- my Dad used to drive a '51 International. His would start fine but as he drove on a cold morning the carburetor would ice up until it was starved for fuel. He'd have to park and wait for the engine heat to thaw it out, then he was good to go. In his case the carb was cracked. Of course our Patriots don't have carbs, but it's been cold here the last few mornings so I bet a throttle body with a vacuum leak might have a similar effect.

 

In this case, might it be a good idea to first try to clean the throttle body plate area? Maybe it is just gunked up, which is exacerbated in cold weather?

 

My first TB went to 270,000 miles. I fixed it just before I sold it. Ignatz is now around 305,000 I believe, so that TB is relatively new. That's why I'm guessing a vacuum leak. My old Pontiac had a sticky TB but I learned to live with it. Symptoms weren't nearly as bad.