2006 Infiniti M35 heater blows cold when stopped but works normal at highway speeds. Any suggestions?

If it is normal temperature, then goes high and back down within a few seconds. The engine is not completely purged of air. What I do seems silly(even told this, but Fill the reservoir, run the engine to operating temperature. Fill the reservoir again. At this point I over fill it. Take the car for a drive to the nearest clear parking lot. Run it in tight circles as fast as you feel comfortable with(20 MPH+). Do this to the left and right a couple of times each. Check the reservoir again and fill. Centrifugal force works wonders on pushing air out of difficult cars. Like Ford taurus's.

as long as its the same battery group it will work

06 M35 is chain driven.
You can also check out these sites for other helpful tips on Nissan and Infiniti:
http://www.nicoclub.com/FSM/M/2006_M45-M35/
http://us.infinitiownersclub.com/
Good luck

It may be your thermostat. When they go out the heat stops. If you rev the engine a bit, or on the highway, if it comes back; you may need a thermostat.

dont know if this will help but it is the only thing i can find.
http://www.infiniti-techinfo.com/refgh0v/og/infiniti/m45/2006-Infiniti-M45.pdf covers M35

if ur waterpump is bad u wont get heat it happend to me on my mazda

check belts and tighten or replace as needed

Cold start it can vary from 800 - 1500. At normal temperature it should be around 400 - 600 rpm depending on how much load (electrical wise) is on the engine at idle.

Check your coolant level. If it is low, what you describe will happen. Water pump works faster as rpm's increase, managing to get hot coolant to heater core (highway speeds). At idle, pump is not working fast enough to get the coolant to the heater core.