My car seems to take ages to warm up, even 30 mins constant driving and the needle can be stuck at 70ish, push it a little and it will sit at 90.

So far i have done the following:

Change thermostat + o ring
Change coolant temp sender


Could my fan control switch be gone?

Also i notice if i sit at the lights or idle for a while the temp will start to drop from 90 for example, down to 70.. it does this in the space of around 5-10mins idle.

Anyone have any ideas? im really clueless here, its annoying when it takes so long to get some proper warm air from vents!

Jay