Ok...I'm at a loss on this one,
My car recently has been having absolutely terrible acceleration off the line (ie: at a stop the car would lag for about 2 sec and then start to take off). So my stepfather did a tune up on the car (new plugs, wires, rotor, and distrib cap). The first day I drove it, it was driving much better, however the past two days the cars is displaying new symptoms that I am at a loss to figure out what is wrong. When I start the car, the idle goes horribly low like the car is going stall but the acceleration meter show the gas at a much higher level than is normal when the car is idling. Once I get out of the driveway, the car not only has terrible acceleration but starts chugging slightly. I have also seen that lately the car is starting to smoke just a slight bit from the tailpipe... This problem goes away after about the first 5 mins of driving but the smoking comes back if I sit at a light or in traffic. The car is a 92 940 turbo with almost 200,000 miles on it. Anyone have suggestions as to what I can do?

Also, check that you can hear a click from the throttle position switch when you move the throttle slightly off the idle position. If it does click, it should be enabling your idle air control valve (IAC) for proper idling, but based on your description, you may want to consider cleaning the IAC, and probably the throttle body too.

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David Armstrong - '86 240(350k km?), '93 940T(270k km), '89 240(parts source for others) near Toronto

Look for a tear in a turbo intake hose (the large black rubber hoses under the hood connected to the turbo and the intake manifold). When this happens, boosted (pressurized) air leaks out and causes the mixture to go very rich, resulting in the symptoms you experience. A small tear may appear only under pressure, so have a friend help you look for leaks.
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See the 700/900 FAQ under 'Select Link' button on the top right.

This sounds to me like a problem with the Air Mass Meter (AMM). With the car off, I would try unplugging and replugging the connection to the AMM several times. While you have it unplugged, check to see that none of the pins have been pushed back in the connector.

Also while unplugged, start the car and see if the bad idle and smoke go away.

Now turn the car off and replug. Start the car and see if the symptoms are still there. If they are, see if you can find a replacement AMM (I think yours ends with 016) and swap it in. This is an easy swap,

Keep us posted.

Check out the Engine Tune and Performance section of the FAQ for more details.

Ian

AMM don't come cheap right? I had one replaced on my 940T also and it ran much better.

AMMs can be had on ebay for about $50, so it's not too bad.

Try out the suggestions from Steve and darmstrong as well.

Ian