I blew a head gasket a few weeks back on my 87' Shelby Z, not the end of the world so I used it as a way to clean up the engine compartment etc.... I got everything back together and running but now it seems to have lost some low end grunt and midrange, vacuum at -22 / -23 when idling when cruising it's around -16 / -19 my AFR bounces around between 10.1 and 13.4 on my autometer wideband. The car starts and idles fine, I set the timing to 12* BTDC when it was at operating temperature, just smells really gassy, plugs are a darker brown color and when I get on it, it feels strong. I know my mileage is suffering my Traveler says I'm getting about 22-23 mpg just taking it easy. Fuel pressure is a static 55 psi, didn't mess with that setting after I pulled the head off. I had to install a vacuum block since I snapped the factory plastic union off the back of the intake, checked for vacuum leaks numerous times. I've checked the timing 3 times everything looks correct, here is the kicker though, when I start it cold it has the normal -16 / -18 of vacuum my AFR bounces from 14.3 to 15.1 which is normal and then after it heats up a bit usually within 5 minutes of driving the vacuum changes along with AFR, here are a list of mods on the car.

Also I noticed that my waste gate solenoid is sucking vacuum through the bleed, is that normal? Found that when I was searching for vacuum leaks.

: Aftermarket blow off valve
: High flow conical air filter
: Underdrive pulley
: Mystery cam (Not sure of grind) on the car when I got it
: Zener diode
: MBC
: Mopar performace computer
: Water / meth injection - pre throttle body / pre compressor
: AFPR
: Ported 2.25 inch swing valve
: 2.5" to 3" down pipe / exhaust
: Boost set at 19 psi
: 160* thermostat

This car ran extremely strong before with no issues, the only addition was the vacuum block

Thanks in advance for any help!