220,000 miles on the injectors is a bit much. I'd replace them.
What are the spec's on the cam?
Check out this article about cams.
You said you washed out the rings and bearings...Were the piston rings put on correctly (alignment)?
You want your AFR to be at 14.7 during closed loop operation. 12.2-12.5 during a open loop full throttle blast for naturally aspirated engines. When driving and then slowing down (letting off the throttle) the PCM will cut fuel to aid in deceleration. This will cause a very lean condition but it is perfectly normal.
What all did you do to the MAP and why? You shouldn't need to mess with this. This will alter what the PCM uses to look up it's proper fuel tables.
You said you replaced your O2's do you have a scanner with the ability to see your fuel trims? long and short term and also view your O2 sensor voltages?
All you should really have to do is match the fuel injectors with your new bore and stroke and your factory maps should be fine and well within the range the PCM can add/subtract fuel using the O2 sensors input.
As for your vacuum issues. Does this reading fluctuate or is it steady? Are there any leaks? How is the vacuum brake assist (brake booster) working? Do your breaks feel fine or soft/weak?
Cams are very very important check out your specs and make sure it is doing what you want it to do when you want it to do it. A badly chosen cam can make an otherwise powerful engine a complete dog. Choose wisely.
Have you sea foamed to check for exhaust leaks and clean the internals?
Have you tried your stock throttle body to rule it out of the equation?
Please post up the full specs on the build and everything you have done and I'm sure we can get it running strong for you.