VERY lean on acceleration

[Kudzupatch]

93 suburban 350, automatic, 185K Sorted out a couple of issues recently. New distributor, egr and just put in O2 sensor. It was running good with an occasional hesitation or roughness from start up. So I knew I didn't have everything fixed but I had the big issue I was having fixed.

Our first cold morning it no lost power on light acceleration, MOST TIMES. I can feel it running rough, probably misfiring. Light acceleration from start, hitting an incline with cruise on or just speeding up, per the o2 sensor reading it goes EXTREMELY lean. I can watch the knock count jump at the same time. Cruising down the road it bounces around as it should. But on acceleration it drops to near 0 and stays there.

I have Tuner Pro but I have been using ALDroid and it doesn't give O2 voltages just a 0-100 scale with 0 being bottom end lean and 100 top rich end. 02 sensor reading drops to nearly 0 or fully lean. I replaced the o2 sensor just to verify this was right and same readings from both. Or sense was very white too.

It runs fine in open loop. My fuel pressure gage went out, new one will be in tomorrow and I will verify fuel pressure. But it runs fine in open loop and under harder acceleration which doesn't sound like low fuel pressure to me.

Engine temp is showing 180-185 degrees on the computer, not my dash gage. MAP reading seem to be normal. Nothing stands out to me.

I will check again for a vacuum leak (done recently). Other than that I am rather stumped. Assuming the gage doesn't show fuel pressure problem.