1988 dodge ram 250 "NO HEAT"

hello,i have a 1988 dodge ram 250 conversion van.it has a 318 engine.,,i had the complete cooling system flushed,3 new thermostats installed,new heater controll valve installed and new antifreeze put in.when in idle at start up it takes about 35 minutes for temp gauge to reach proper tempture.but my defrost is blowing out luke warm air and the same my vents.the controll is max on high heat along with the blower.when im driving it puts out great heat,but when i come to a stop or slow down it blows luke warm air.ive been to 3 shops,spent over 400 dollars and no one has fixed it yet.i just paid them too look at it i guess.then someone said to replace my "PORTED VACUME SWITCH"that operates my heater controll valve but my hose is hot on both sides of the heater controll valve and the top hose that comes from my heater core going to my engine is also really hot.THEIR HAS TO BE SOMEONE OUT HERE WHO KNOWS HOW TOO FIX THIS PROBLEM,FOR THE SHADE TREE GARAGES HERE IN OHIO SURE DONT KNOW ANYTHING AND IT IS COLD AND SNOWING HERE AND ID REALLY LIKE TOO FIX THIS PROBLEM.CAN ANYONE PLEASE HELP,,,,,COULD I JUST COMPLETLY BYPASS MY HEAT CONTROLL VALVE,OR COULD MY HOSE"S THAT GO TO THE HEATER CORE BE PUT ON BACKWARDS LIKE MAYBE THE BOTTOM ONE GOES ON TOP OF THE HEATER CORE.,,,,,MY TEMP GAUGE STAYS BETWEEN HOT AND COLD IN THE MIDDLE AFTER WARMING UP.IT DONT DROP OR RAISE.ALSO IT DOES NOT HAVE A FAN HOUSEING OVER THE FAN BLADE EITHER.COULD THAT BE A PROBLEM WITH NO HEAT,,,,,,,,,,,,,,,,,,,,,,THIS IS A REAL MYSTERY,,,,,,,,,,,,,,,,,,,,,

THANKS FOR THE HELP,

SCOTT

 

Sounds like a vacuum problem. If there is a vacuum leak, or hose broke, there will not be enough vacuum to open/close the blend door. What I think is happening is:

When you are idle or not enough RPM's, there is not enough vacuum to keep the blend door valve open/closed.

When you excellerate, you produce more vacuum, and this allows the blend door to open up fully to allow heat in.

 

try flushing out the heater core