kdr3885

95 c280 with 189,000miles (acquired in May). When bought,RPM would constantly oscillate when at idle. Tracked down a couple of loose/detached vacuumhoses on the engine/manifold and reattached. Car now shifts through all forgears. JInstalled new plugs, new air filter. Usedsome throttle body cleaner on throttle body. Installed new Bosch MAF censor and oscillating rpm ceased. J A few weeks later the rpmstarted oscillating briefly (5 or 6 times) a few seconds after the car wasstarted, L thenrpm would settle down. It does thisevery time the car is started. When the car is started in the morning (enginecold), its starts, goes through the 5 or 6 oscillations, settles out, then runsjust fine. When the car is started later in the day (engine warm), it starts tooscillate and immediately dies. It willdo this unless I rev the engine for a few seconds to a minute. Engine may berunning a little rougher than when first purchased. Any ideas?

ptcruiser

Sounds like the air pump may be a problem. It's designed to operate when you start the car in the morning, but then shuts off. The RPM's should be around 800 on idle.
Sometimes there is a bad electrical connection, or it's dirty.