94 4.3 CPI Blazer is getting on my last nerve

[towbar]

Hey guys, I bought this 94 CPI 4X4 Blazer with 104k miles on it a few months ago, it was running great but gradually started running rich and was hard to start. I checked the fuel pressure regulator by looking through the plenum divider in the top of the intake and the regulator was leaking (dribbling and puddling). So I pulled the upper intake and replace the regulator with a new Dorman part and FelPro gasket from Autozone. Fired up and ran great that day, the next day while driving the engine shut off. Tried to restart and it was hydrolocked with fuel. Hauled it home on the trailer. Looked into the intake and the intake was filled with fuel, once i got the upper intake back off and cycled the pump I saw that the new regulator diaphragm had ruptured and would actually spray fuel on the garage wall. So I pulled the regulator, returned to Autozone for refund, went to Orielys and got a Borg and Warner regulator. Spun the engine over with the plugs removed to make sure there wasn't any obvious internal damage and to get the fuel out of the cylinders.....everything seemed fine. Installed the new regulator yesterday and buttoned everything back, changed oil, installed new plugs, it fired fine and idles smoothely for about 10 seconds but then started missing and ran terribly, no power, missing horribly at part throttle, occasional backfiring through the intake, lean O2 code showing.

I dont think there is any internal engine damage, it idles pretty smooth with an occasional miss, no noise from the engine. Dosent overheat or puke out antifreeze. No oil in the water. Have not done a compression check though.

I did verified the firing order making sure it wasn't cross wired.
No obvious vacuum leak showing up but there must be one to cause the lean condition.....any ideas??
Should I have replaced the day old intake gasket again??
Could it be leaking?
how many # of vacuum should it hold at idle? gonna hook up a vacuum gauge tomorrow.

there is a tear in the rubber boot that connects the air filter assembly to the intake throttle body but its been there since I got the Blazer...maybe its a little bigger now from repeated on and off....could that tear be causing the lean condition?

think I'll spray the intake down with soapy water and put some compressed air in the intake through a vacuum port and see if i get any bubbling

thanks in advance...any help or suggestions would greatly be appreciated!!!!