stalling when coming to a stop

Hi everyone. I put in new t5 tranny gt40p heads and explore intake and roller rockers had to go wth taller valve covers, got trickflow valve covers with oil breathers in each one. I blocked off the tube coming out of the throttle body. when its warmed up and i come up to a stop it stalls. It has a adjustable fuel regulator and is adjusted to 40 with the vacuum hose on. does anyone know what could be making it stall. it was also a little low on coolant and running a little hot. thanks