peterbilt 362 wopping my #####

hi guys. im new to this group and am having some pretty big problems with my 1988 362 pete. first off I had to put a new heater core and blower motor to get heat. I can get hot in the cab when parked but when I start driving it gets cold inside. the engine temp is at 180 and still cold inside but it blows warm air. I cant get my windshield to defrost. almost like not enough air flow. I plugged all the other duct work except the defrost and still not getting good air flow. I even added a pusher fan in the heater box and it helped but not much. I don't think I am moving enough air thru the defroster but its not plugged anywhere. and the core is hot. next issue is the windshield seems to move on the drivers side pillar when I make a left turn and apply throttle. almost like its flexing the cab and worried about the windshield falling out. any ideas on these issues would be help full. its hard to find info on the 362 let alone a mechanic who has been around them. thanks guys

 

brand new heater core so its not the core. brand new blower motor so its not the motor. I pulled apart the duct work and sealed it all up. also manually moved the selector for the flaps to make sure it moved all the way. maybe I need to pull the whole heater box out and open it up and look inside it.

 

put new glass and new seal in over the summer. less than 6 months old on the glass and seals. also my glass shop put urethane in to help seal it up and make it nice and tight. didn't start this problem tho till it got cold out.

 

been thinking bout replacing the door seals. they are worn out.

 

I can tell its the windshield moving because I can watch some of the urethane stuck on the windshield and it separates from the rubber trim. can watch the gap in the ruber and urethane grow then shrink as im shifting gears while making a corner to the left.