Fuel issues

[Cat11]

Hi All

My 85 325 is misbehaving...400,000+ miles...new head, new clutch, new etc &c.

It's a fuel problem which my mechanics can't figure out. It goes a few miles, then behaves like it's running out of gas & quits running, while bucking like a horse as I downshift. If I leave it alone for 15 minutes, it may or may not exhibit the same behavior.

Have replaced the cc, the air flow monitor

The big problem is....it's totally random, and obviously a fuel issue

As everyone knows, once you bring a car to a mechanic, it will not display symptoms...and the car will not work!

Any advice?