Idiling and overheating problems with my 92 318i

Hi all,
I have some problems with my 92 318i, Ill just get into the two most important ones here!! I am a novice so perhaps excuse my ignorance.

1. The engine revs up and down when idiling, especially bad when cold but it could just as easily happen after a three hour drive. Also, when i come to a junction and need to take my foot of the acelerator, the engine can sometimes just cut out. Again usually worse when cold
Any ideas?

2. When sitting in traffic, the engine overheats quite severly!! I have had this checked out and told all is fine.. Personnaly i feel the pump is gone or there is a blockage, the top hose feels like it has nothing in it and is hot after a journey. I have tried bleeding the system, and have got air out (Could be steam eeekk..), The only method i have of curing this is to turn on the heater and take the heat into the cabin, not so comfurtable on a hot day... Ther is no problem when crusing along.
Any ideas?

Id appreciate any sort of feedback at all, and preferable some advice on what to do, im not a mechanic but pretty handy and will give anything a try and would very much like to solve these myself if possible.

Cheers.