is it a 8v or a 16v? I had same problem, and turned out to be the TPS not being set right. There is a switch that must close when the car is at idle, to tell the ECU to change its ignition and injection graphs. There is a quick test you can do, for a 16v:
-Pull the plug off the tps
-make sure battery neg is disconnected
-there are 4pins that run vertically inside the plug, number one pin being at the top and number 4 at the bottom. Get an Ohm meter and test the resistance between number 3 and 4 (bottom two pins)
The resistance must be less than 300ohm, but preferably around 30 ohms.
- if resistance seems a little high then get a feeler gauge of .8mm, and sit that between the throttle stop and throttle.
-then loosen the two little bolts on the tps until it will just move
with the ohm meter still measuring the resistance of those two pins, you want to move the tps gently until the switch is making a proper contact and reading that 30 ohms. when you feel it is good, tighten the two 8mm bolts up and remove your feeler gauge.
- double check the resistance is still sitting in the same range
-start car to make sure idle is correct!!
Now thats a rough description, but you can try:
http://www.kick-fix.com/dies.htmlhope this helps!!