Ken, if the coolant resevoir is too low you may still have issues with air
trapped at the top of the coolant hose 90 degree bend exiting the front of
the head.  Ideally, the smaller hose branching off and going to the coolant
resevoir should flow uphill to the top nipple on the tank.  That is nearly
impossible with the stock resevoir due to the lid height restriction.
Either way, air will always sit there if it can't flow uphill to the
resevoir.  You may want to "burp" the coolant hose there.  Given the I4
design, there is no where else for air to sit.

After sitting for a few months I took my van out for a "winter blast" and
had poor heat but normal cooling.  Burping this hose and doing the old rev
and bleed procedure fixed this...