I have owned one of these since 7/01 and 17miles. Now have 189k on it. I can only offer up my experiences as I have thought at times that I had a rough idle. First and foremost, it will NEVER idle REAL SMOOTH. I think all you can do is get it to idle AS SMOOTH AS POSSIBLE. To that end, you don't say how many miles are on the car, I would most definitely check for vacuum leaks. Also, on the passenger side, behind the washer fluid bottle are two solenoids that control vacuum, one of which is the vacuum advance. There are check valves in line with each of these solenoids. After 18 years,I checked this visually and found I had a cracked check valve, replaced it and it idled SMOOTHER. Replaced BOTH solenoids and all associated hose fittings and VOILA....a "smooth" idle. You might also want to take a look at your distributor cap and rotor and spark plug wires. I can almost guarantee that new Bosch COPPER plugs (H9DCO), distributor cap, BERU wires, and a fuel filter will also help tremendously. I have used Bosch wires but they don't last as long as I have found the Beru's to last. Also, if you have high miles and original fuel injectors, seals and o-rings, then they too can be suspect. Once you get all of this done you will be surprised at how smooth and powerful this thing can be. Good luck