Hey Lom, welcome mate.
These are fairly complicated cars to work on, for most maintenance you will need a scanner to diagnose, especially handy with faults like yours. I would start with making sure the revs are correct, it could help with the stalling to clean the throttle, but be aware, don't move the throttle plate when you do.
Have you checked the plugs at all? What mods have been done? Havs the engine light been on at all?
Probably best to get it checked over by someone who is familiar with the M35, there are a few common faults to look over which most have by now. Things like sway bar links, compression rod bushes, passenger side rocker gaskets and others will most likely need replacement if they haven't been done already. Where are you located?