EG civic w/ B18C5

Running fine, no issues. No CEL's

Basically, I was driving on the freeway for about 15 minutes yesterday, took the off ramp downshifted to 4th slowing down and the car just shut off.
No weird noises or anything that I noticed.

So I coasted down, pulled over. Tried starting it and it fired right up.
No problem. Didn't do it today either.

What should I be checking?

 

From the sounds of it. It sounds like it may be an ignition problem. You may have bumped the key inadvertently shutting the car off.

 

lol

The key was in the complete forward position, I think I'd notice if I turned the car off.

I've also noticed, when the motor is cold. If I give it done gas and rev it up to 3k or so, the rpms will drop down and the motor will almost die...
Doesn't do it ones it's reached operating temp though.

 

I would check the tps I had a car do that for awhile untill I just totally died and come to find out it was tps. Just sounds like you have a sensor giving a bad read