M3 cooling issues? Help please

[M42]

Hi guys, hope someone can help with a little issue im having on my 87 M3. since i bought her the electric fan would alwaysbe on low speed, i did a bit of research and was told by a few including Munich Legend that thats the way it should be. I didnt like the idea of that so i bought another temp switch and now its always on High speed! Then i tried a double temp switch (91-99 degree) switch and now nothing coming on at all. It got me thinking maybe the stat isnt opening to let the hot coolant into the rad, cos the toop hose is getting hot but the bootom hose from the stat to the rad isnt. switch is located in bottom of rad and heaters blow hot too, whilst deiving the temp guage sits just below half and when idling around half or sometimes three quarter. m i missing something or is something not quite right on the car? Thanks and sorry for the essay.