Strange problem with 325is

[325isBMW1988]

When i first start the car it will idle fine but once i start to drive away it will bog-down but the engine wont stall or anything it just bogs. then, once the engine warms up a bit, it will run fine and feels like it did when i first got it. every once-in-a-while when i take a 30 min. or so ride around the area it will start boggin down. its fine if im just barely giving it gas but once i hit the gas hard its as if im half-way with the gas pedal. i narrowed it down to either the Throttle Position Sensor or the Idle Speed Regulator. can someone help me out?

[witeshark]

How long since the ignition system has been serviced? Has the intake boot been checked for cracks? When idling, the M20 throttle is closed; idle air supply is by way of the idle bypass (fairly easily seen on the throttle body).

[325isBMW1988]

isnt the idle by-pass the same thing as the idle speed regulator?

[witeshark]

It's actually a fixed, separate intake bypassing the throttle section. It's easy to see it on the throttle body.

[silversled]

I would most certainly do the obvious cheap things to clear this one....check wires and so forth, do a tune up (start with the plugs only) and keep moving forward...my guess is either a coolant temp sensor or an air leak as mentioned previously...good luck