Hey guys, my DC2 b18c2 has developed a weird pulsing idle.

The problem happens randomly, sometimes doesnt happen sometimes its constant.
The revs sit at 1500 and it's like the pedal is constantly being tapped. Makes the car jerk constantly at 1500 revs.
Have checked fuel pump, changed plugs, filters and leads.
Doesn't lose power or anything.

https://youtu.be/FuRmphA4CyU

Any info would be greatly appreciated.

Thanks.