I've got a 93 4Runner that's been having some issues with overheating and idling. The idling issue is most noticeable in the winter. When warming up the engine, it will idle high (between 2-3k) for a while. The rpms slowly go down and at some point it will start revving up and down. This lasts for about five to ten minutes before it will finally settle and start idling at a normal rpm. In the warmer months, this behavior seems to have mostly gone away, but now the engine is starting to run pretty hot. There does seem to be a coolant leak, but even if I've just topped off the coolant it will still run hot. Just getting into the red. Might these things be related and what are some potential culprits?