So ever since I've converted to e85, randomly at cruise and if I hold partial throttle for a while, my wideband will completely read max lean. The exhaust will sound like a deep drone and the car will have very little power. But once I release or blip the throttle. It will return to normal.

Some days it's worse than others, never really consistent. Any ideas what it could be?

 

Sounds like you could need a tune touch up, or you pump is starting to go out

 

I had a problem very similar sounding to this on my 06 sti when i put used dw850's and a 20g turbo on it. Just cruising around at steady throttle if i tried to accelerate at all it would jump lean and the car would stumble/loose power. If i blipped the throttle or stepped on it, the afr's would richen back to normal and the car would drive normally. It was the weirdest thing.
My Tuner tried richening the fuel tables in the rpm range where it seemed to happen the most. This helped but only put a band aid on the problem.
My tuner thought it was my rear o2 sensor gone bad, but we checked that and it was fine. Next, we tried replacing the Fuel pressure regulator, and that didnt help either. The only other things he could think of was that my new (used) injectors were messed up or dirty, my fuel pump filter was dirty, or my fuel rails may be getting gunked up. So I went for the easist option, I put my old oem injectors back on and the problem was gone.