BMW Repair: 96 323cut out probs, rule of thumb, rev counter

Question
hi evan,
i have a '96 323 coupe with 121500k, wont start "sometimes" when hot, will cut out when cold after setting off (but only sometimes and when going up a steep hill most commenly). rev counter, mpg gauge and temp gauge will intermittingly malfunction reading nothing. used to splutter and missfire until recently changing the spark plugs. again intermitingly low revving has low power(much slower in pulling than normal) but will "go like hell" up the rev range from 3500-5500 and then it would hold back and give no more. have been finding white sludge (sometimes) under the filler cap for the oil, but temp is fine, drinks no water. i pressure tested each cyl when doing the plugs, 14 bar in each 1 roughly, just 4-5psi difference between lowest and highest, is that ok? one day when it wouldnt start(when hot again) when the ignition was on there was photocopier type noises coming from underneath the car, the fuse/relay box, and the top of the engine underneath the rockercover cover. nearest bmw garage is 120miles away but not too confident of the car making it there.
any advice or answers would be greatly appreciated!!!!!  

Answer
Andrew, check the idle valve for freedom of movement. If the car doesn't start try tapping on it with a metal object and retry. Rule of thumb for cylinder to cylinder deveation is no more than 15 percent. Also could be a DME, injection or ignition relay that is funtioning intermittently.
-Evan