Check/clean all connectors under the hood.

Check the connector on the distributor...could be cracked/deteriorated. (Cheap $4 fix).

Clean the throttle body.

Check for vacuum leaks...wouldn't be surprised if one or more hoses, like the one from the turbo to the tube to the intercooler, is deteriorated and/or loose clamps.

The ignition amplifier or ignition module (thing with heat sink on it, right under FI ballast resistors on left side of engine compartment) should be failing about now, although generally when it fails you have lights on the dash...