My E23 2.8i auto is driving me up the wall!!!!

It has been running very well after changing all the intake/crank case breather hoses and now has developed a new problem. Yesterday I had a hell of a drive to Lincoln to classic car pub meet.

On light throttle, 50/60 MPH it keeps cutting out. At 50/60 pump the accelerator a couple times and it keeps going. At 30 MPH or lower it just dies and very often wont start. Not enough speed to drive the engine through the auto box. Hell to drive in stop go traffic.

I have checked all under bonnet electrical connections and all are in very good condition, I spraid them with electrical contact cleaner including the ignition brains under the washer tank, what a damn stupid place to put the brains and coil. I was told there is earth lead behiond the glove box but could not find one. All in very good condition, no water marks.

I have made up 2 new earth leeds. one from exhaust manifold to coil bracket and the other from dip stick to body, all for nothing.

I have been told it could be the air flow meter, is this the problem?  If it is has any body got a good one for sale? If I have to buy a new one it will be end of car