Edge perimeter not sticking to last layer properly..?

I'm having an issue with this black ABS on my Prusa i1 running Marlin on Gen7 and gregs extruder.

Has anyone come across this and is there a known fix?

It tends to do it less at higher temps but the accuracy of the model is lost due to seeping I think. This picture is of a 205c temp extrude, I tried at 250c and it's a bit better but not there yet. Printer printed with other orange ABS without this problem.

I tried to slow down the last perimeter to 35mm/s instead of 50 and it doesn't seem to have helped.

Thanks

I just tried blue abs from the same supplier and it's acting the same. Might try printing much much slower and see if that helps.

Should of stuck with the more expensive supplier!

Printed at half speed (half of what I was before 40 perimeter, 60 infill) and its much better, but still just a couple of lifts...