My buddy had a stock landcruiser that would loose vacuum when he stepped on the brakes. I suggest getting a BIGGER VACUUM CAN. If you have a bigger engine you need a bigger can to hold the Volume of Vacuum needed. Look in a Junkyard and find one or two vacuum canisters. Steady Vacuum is your friend.
You might also talk to a local Radiator Shop and see if he has a Bigger Radiator. Maybe made for a landcruiser with AC and an Automatic Transmission. Even if you dont have AC/Auto Trans... the larger radiator could help remove the heat. Until then... just ride around with the cab heater on full blast and the windows open.
