Big Or Small Problems With Trac Light On And Off?!

[SCRider]

Ok this problem has been with me for months now and I really don't know what is wrong with the car. I have a 92 sc300 and here's the short version of it. A few months ago my alternator died so I figure while I change that I mind as well change the spark plugs, wires, dist cap and rotor, and serpentine belt. After all that my idle was too high and when I'm at a complete stop and start to accelerate the car starts to stutter, the TRAC light also on. So I took it to one local mechanic and they changed my pcv and my throttle sensor. Problem still exists, so I then took it to another mechanic that specialized in foreign cars and they adjusted it for me and the car runs fine. Now every so often the TRAC light goes off and my car stutters again, but then I drive it a few more times and TRAC light comes on and the car drives fine (please keep in mind that the mechanic adjusted my idle and throttle timing with the TRAC light on). OK so how do I fix this problem? Will someone please help me.