2006 Grand Caravan, 3.8 6 cylinder.
Check engine light is on.
Scan tool reveals no stored codes.
With engine running in Park, RPMs are limited to about 2800, cuts out above this.
When you drive it, RPMs will go way above 2800 as it shifts out.
Another problem that seems to be related is that althought the engine temperature gauge will show normal, the cabin heater will not blow warm air unless you rev the engine to around 3000 RPM. Then you can "feel" something happen and the temperature in the vents increases and will stay warm until the RPMs drop down pretty low. I can't help but feel that these problems are related somehow.
Does anyone have any suggestions? Thank you for your help.

 

Welcome to DF
You may have a huge vacuum leak and should have it inspected.

 

The air selector for vent, defrost, floor, etc. works at idle fine. Is this vacuum controlled? Is the heat temperature out controlled electronically? The AC works fine

 

Does your scanner ck codes in all modules? I'm sorry but i thought you were having high rpm in park. The reason the engine cuts out in park with your foot into, is because all vans and cars have rev limiter that cuts out at 3,000 rpm. So you won't blow the motor. And reason why you can go above with transmission in drive is because the transmission is putting aload on the motor, Park no load.If you are having a heater problem, replace the thermostat first.