'88 5 series... hesitation,can you help?

[slc ya]

Ok... a friend of mine has an '88 5 series (can't remember the number), but it has an e after it and a 4 cyl engine. Anyways, he can't seem the get rid of this problem. It seems to miss every once in a while, of course it is especially noticeable under acceleration, but the hesitation is there even when crusing at highway speeds. It might do it 3 times with in 25 mins... or not do it at all for a whole day.

I told him I would see if any of the other BMW enthusiasts had any ideas about stuff to check. Other than that problem the car runs great...
thanks a bunch-ERIN

[SimonP]

Check for loose or damaged ignition leads. If possible test them with a multimeter. Depending on length, you should get a resistance of between 5000 and 15000 ohms between the ends of each lead. Sometimes the carbon based core of these leads breaks down, and the spark has to jump a gap inside the lead.
The resulting spark at the plug is adequate for the engine at low loads but will not ignite the fuel under heavy load, ie acceleration.

Also check that the rubber intake hose between the throttle housing and the air filter is not split. If it is, the engine will draw in unmetered air and therefore the incorrect amount of fuel will be injected.
Torque on acceleration usually causes any splits in this hose to open up, giving the same symptom as you described.