Breaking up while cruising/running lean and shutting off?
 

I don't even know where to start with this. I've started daily driving my Evo IX for about 2 weeks. I'm waiting on a reflash from tscomp since I added a BR stage 3 head. With that being said, I've had zero issues so until 2 days ago.
I go to start the car, it starts and reaches idle rpm range then dies. It did this 3 times. I let it sit for a minute, start it up and idles like a champ with no issues.
Yesterday morning it did the same exact thing and same results. I figured my IAC was on it's way out so ordered one (should be here Friday)
This morning after work, I cross my fingers and it starts right up the first time and idles smooth. I'm freaking pumped and start to head home. I hit a light. When light turns green, I accelerate like I normally do and when I hit 2nd, the car "bucked" and I noticed my AF gauge reading --- on the lean side and the best way to describe it is it felt like I was in neutral with zero acceleration for a few seconds until the AF gauge jumped back down to 14.7-15.0 like it usually stays at. I'm speed density tuned and it reminded me of a huge boost leak. I finally get to 5th gear and back at normal speed and A/F when all of a sudden the gauge would peak 18+ AFR and loss of power again. **No check engine light at all**
I pull over, turn the car off and pop the hood and checked everything, crawled under the car to make sure my LICP didn't pop. Everything was sealed.
I hop back in my car, start it up (starts normal) and nervously hop back on the road. I accelerate and all gears felt good and smooth. Another redlight...go to stop..car dies completely. I hurry up and start it back and waited for light to change. Start heading back home, no issues.
I also noticed when I would come to a light, if I put the car in neutral and coast to a stop, the rpms seemed to drop slower than it usually does (Exedy Twin/Flywheel all rebuilt)
On a back road I try my luck with using some boost and hit 11.0 AFR and it pulled like a champ. No hesitation like everything is completely normal.
I'm working night shift this month and have been up since noon yesterday and going to get a nap before I check things out.
My idea, the car has been sitting off and on for almost a year. When I got it back running, I changed all spark plugs and haven't had a single issue. I'm thinking besides my IAC dying, possibly my o2 sensor going bad and possibly bad spark plugs.
Has anyone ever heard of anything like this happening before? I searching the forums but really can't even describe this issue. Any other suggestions? My car hates me and the feeling is mutual. I think there is a pissed off gremlin that hops in my engine bay and destroys parts overnight. Went to gas up yesterday, my damn gas tank "spring" popped off and the plastic split.
Also with all these issues, the walbro fuel pump was on the car when I bought it with 11,000 miles. Currently has 80,000 miles. Maybe the sitting so long wore the pump out all of a sudden?
Sorry for the long post but would appreciate any guidance on fixing this. Also I used the same gas station as I always have and never had an issue with bad gas if that helps any.

Now would be a good time to invest in a remote fuel pressure gauge.

I don’t know how to post instead of replying but my evo 8 mr shuts off while driving
 

Can you list the mods done to your Evo?

What the mileage of the car? Your IAC which is located on the throttle body! It probably don't fully actuate. Take it out of the throttle and turn the key on to see if it move, try to record it with the camera on your pone. If it barely move that your issue. Check youtube

I would check the plugs to see if there are firing and do you have COP set up? Maybe the coil pack going out too

Check:
1st.
Ignition coils and wires
Spark plugs

if 1st is good:
2nd.
Fuel pump (filter)
Fuel?(moisture)
Injectors(gunk up)

Good luck

Check the BISS screw on the throttle body as well and raise your idle slightly. Also your injectors might be dirty and need a cleaning. I'm sure after the tune it will run a lot better.

I would start by checking the easiest item to check - fuel pump wiring and fuel pump housing connector.

I had the same issue as you described and kicked myself that I spent so much time checking other items before checking the fuel pump wiring.

Pulled the connector apart that's on the factory fuel pump housing and it was all burnt out and full of moisture. Sometimes it would make a good connection and run fine, other times not.

Takes 5 minutes to pull back seat out and check the connector under the black plate. Make sure you pull the connector off the housing because at first glance it may look fine.