My car seems to change with the weather! Seems like in the spring when it's cool the idle RPM's surges but only sometimes. Instead of Idling at 800 it will drop to 400 and you swear it's going to die, or it may surge up to 1200 and then fall back after a sec or two. When it gets around 70* car never has a problem.
Dirty Maf was a thought but why would it act crazy one day and not the next with the same air temp?