p38 4.0 v8 with lpg i need help before i end up in looney bin. head gasket blew got it changed by good engineer but now it wont run for more than 20 mins. car starts on first turn of key runns great for 20 mins and then stops wont start again if i leave it for about 15 mins it starts great again...

please help before i tear anymore of my hair out. p38 4.0 v8 with lpg just had head gaskets done and rebuild done now car wont run for anymoe than 10 to 15 mins and cuts out as if the fuel has been turned off it does this on both gas and petrol have tried every combination i can think of turned...

I have a very strange problem and looking for help heating works fine for about the first hour of driving and then the drivers side starts to blow cold air out of the vents. It doesn't mater if the heating is on auto or not it will blow hot out of all vents then after about an hour or so starts...