Hi all. Newbie here with an ST200 with a running problem so any help will be appreciated.

Basically, when you try to press on, under 4k rpm the car has what feels like a slight mis-fire. It clears itself after around 4k rpm and pulls clean and hard. Its ok when you keep the revs low and do low rpm gear changes, but as soon as you give it some throttle, it gives off like a "cough" effect and feels hesitant. When you come up to a junction that you need to slow down for, but know you don't need to stop and could pull out, normally you could do this in 3rd gear with part throttle, but with this problem i would need to be in 2nd or it starts to jerk quite bad until it clears itself.

On idle, the car is bang on, and revs clean. The problem only happens under load. Ive had the car on the diagnostic and it came back with an EGR problem.

I was thinking plugs and leads as a start, but not sure why it only does it low down, under load, but not at idle etc if it was a plug/lead issue.

Any idea's on stuff i could check as i don't fancy chasing problems forever when it might be something simple.