I have 6 to 8 lbs. It dies over 8 lbs. Also it runs good cold and bad when it warms up. Does the vaporizer need to be rebuilt?

If this has the Nissan K21/K25 engine with the NIKKI regulator,on top of it is a 17mm hex with the engine off and fuel lines purged of LP,remove the 17mm hex and put a guage in this port,you should have about 4.5 PSI fuel pressure at ALL times while the engine is running and under a load.