Blazer stalling out at odd times

[Rob68c10]

I have an 88 blazer with the stock tbi 350. It starts and runs excellent. Idles fine. However it stalls out at weird times. Sometimes if I floor it, it will speed up but when I let off it dies. It has also cut out on me when I had it off camber a little. Then it has also happened after doing a donut in the field. the truck will fire right back up and never miss a beat. I have changed the fuel filter. It has also had plenty of fuel. One thing I have noticed too is the overflow hose from the sending unit back up to the filler neck is missing. Would that cause a problem with internal tank pressure?