I have been working on a 1996 dodge stratus 2.5l v6. Car came in as no heat job. First things first checked the coolant rusty as could be. Spent a large amount of time flushing the fluid and heater core. Put fresh antifreeze and new thermostat in. I did check the thermostat for proper function before installing. It opens at about 185. It is a 180 degree thermostat. I used the lisle radiator funnel and do not have any air in the system. The car will not come up to temp. While under normal operation. If I high idle the car it will come up to temp the fans come on and the heat works good. Once any air goes through the radiator It won't come up to temp. Has anyone experienced this or have a guess at what can cause this?