I also advise you to check the IMRC system. If the linkage from the dashpot is extended when at idle, the engine will run considerably worse below 3000-3500 RPM. This could cause the stutter or make an existing problem worse.
The vacuum solenoid which controls the dashpot is prone to dying although sometimes the linkages just fall off.

"Those who cannot remember the past are condemned to repeat it" -George Santayana