No heat unless going fast

I have a 2006 Dodge Magnum. I've replaced the
tstat, flushed the heater core and the hoses,
replaced the water pump and the blend door
accuator, the cars heat hardly blows hot unless I'm
moving fast, even then it's still like a/c. I also think
it's having a PCM problem, the car hasn't been
recognizing what gear I'm in on the dashboard I put
it in reverse and it won't let me go into reverse and
it showing that I'm still in park on the dash also it's
very sluggish at times and a couple months ago I
gave me a code that said the car thought I was
missing a wheel is there any possibility that these
could be linked to a bad PCM ? It was flashed like 3
or 4 years ago. Help I can't go through another cold
winter with my 2 year old !