last year I replaced the headgaskets in my 5.4. after putting the engine back in the heater didn't work. at the time I had a login to ford's tech website and went through all the correct bleeding procedures. I raised the front of the vehicle and ran the engine with the radiator cap off until the engine reached operating temp. after still could not get any flow through either heater core. I took the heater hoses off and flushed both heater cores with bleach solution several times one core at a time. I could see no evidence of any blockage in either core. i hooked everything back up and ran through the bleeding procedure again. still no heat and the hoses aren't getting hot past about a foot or so. I took a heater hose off with the engine running and very little flow. if you let the engine run for awhile with the heater off then turn it on you will get a little heat but it won't keep up with normal vehicle operation. I put a thermostat in even though the engine water temp is correct, put a water pump on and blocked off the rear heater core. still won't heat even with just the front core. I'm using felpro gaskets i purchased from orielys. since i did everything I could think of with the engine in, i pulled it back out and pulled the heads back off. I checked the gaskets and they are in correct. the right is on the right passenger side and the left is on the left driver's side. I compared the new headgaskets with the gaskets i put in last time. i could really use some help if anyone has any ideas or experienced this. thank you.