Noticed this on friday afternoon after work. Car splutters and battles to idle, reduced power and shaking until it warms up.
Anybody else ever experienced this? What should I look at first? Vehicle is a 96 328i.
I had similar issues with my e36 325i and it turned out to be sensors.
Have a look at your cam and crank sensors and especially check the wiring insulations for breaks as they get bad over time with the heat and age of our cars.
Like @"akash" said, get your codes read first if you can.