I have a 2001 Grand Cherokee. I tried starting it this morning and I was having problems due to the cold, so I tried again and it started. As soon as it turned over the check engine light appeared and was flashing.
The Symptoms:
1. My whole jeep was shaking violently at an idle as well as driving (the engine light was switching from blinking to just being on the whole time)
2. Trying to accelerate was extremely difficult
3. I could not pass 2k RPMs (so trying to drive to my destination at a 50MPH speed limit was very difficult)

Nothing was leaking nor was my jeep smoking.

About 4-5 hours after I got to my destination the jeep starting perfectly fine and ran mint. But the check engine light was still on. But it is not blinking anymore.

If someone knows what this please let me know!

 

Welcome to CF!

The first thing to do is find the trouble code that is set in the computer. In order to do that, turn the key on until the warning lights light, then off, on, off, on again and wait. The code will appear in the mileage display as a "P" code. If there's more than one set, they will appear one after the other. At the end "done" will appear. Come back and report.

OR... you can get someone with a scan tool to get a readout.

 

Blinking check engine light means one or more cylinders is misfiring. This is one you want to figure out fairly quickly, because it means you're sending unburned fuel down the the cat converter, which is hard on them. Usual suspects are a spark plug or coil pack issue. You can start cheap and put in new spark plugs.

 

A blinking check engine light means eminent danger to the catalytic converter. Do not drive it like that or you will have a melt down.

 

Clean your battery terminals.