I have a 03 Chey Express 6.0 with a HM 4.8 w/Salsa. I only heats up to about 160 on regular and then when I turn it to salsa it drops and stays to about 145 even if I switch back to regular heat. I have run vinegar through it twice & all fiber rinse but no changes. The temp gauge on the van dash it at 210. There isn't any build up inside of the normal/salsa valve. HM said it could be the van's water pump but the vans temp is normal. The only thing about the water pump is there is a leak in the water pump when it's hot and you shut it off it does leak a little coolant but just a little bit. Could the water pump still be the problem or could you suggest any thing else ?