Problem with E30 318i cutting out

Hi I am new to the forum and would really appreciate some help here. My 1990 318i (M40) cuts out after 10 minutes or so. If you let it cool down for an hour, it will run again for 10 minutes. The problem started after a service. the following parts have been changed; cam belt, plugs, distributer, plug leads, air filter, fuel filter, temperature sensor. Fuel pressure was checked OK. A second hand airflow meter and ecu were tried with no change. No codes are showing up except catalytic converter which was never fitted to this model.
I still suspect the airflow meter may be the problem. I have checked the resistance on the potentiometer which is operated by the air flow flap. The Haynes manual says the resistance should increase smoothly when opening the flap to full. Mine does not. I unplugged the maf and checked resistance between pin 2 ( the potentiometer wiper arm) and pin 5 (the bottom of the potentiometer track) With flap closed it measures 40 ohms. When I push the flap open a little (15mm at the flap edge) the resistance increases smoothly to 1100 ohms, as I increase the flap opening to 20 mm the resistance reduces to 800 ohms, it then increases to 1200 ohms as I continue to open the flap and stays around that value until almost fully open when it suddenly reduces to 400 ohms, then at the very fully open position it increases to 800 ohms.
This does not sound right. Could anyone please check and compare results with working maf. Any other suggestions would also be greatly appreciated.

Hi Andrew, Thanks for the prompt reply. I don't think the M40 engine has a throttle pot. I think the accelerator pedal is connected by a cable to a butterfly valve. There is a throttle closed and fully open switch OK which could be the problem.
I would normally have thought that the MAF pot reading should change linearly with angle of rotation except that on inspection, there are 11 printed circuit connections to the carbon track distributed around it.
Regards,
Ken

Sorry, I got confuzelled. (it's easily done....)

I was thinking throttle pot but you were quite clearly in your original post talking about another pot altogether.  D'oh.

The same applies to the airflow meter pot as what I was describing to the throttle pot. i.e. the pots should behave electrically in the same way with a smooth change in resistance.

Problem Solved!  It was the battery!! I don't understand how but when the battery was replaced the problem went away. I put the old (18 months old) battery back in the problem returned. I put the new battery  back in and the problem went away again. I have been driving for a week now with no problems. I put the suspect battery in another car (Toyota starlet) and after driving a few miles the engine cut out with a burnt out alternator!! The bad battery was perfectly capable of starting the engine. I hope this might help someone sometime! Thanks for the advice.