flat spot between 3-4,000 RPM 1987 1.8 GTI CAB

They run best on super unleaded and if timing set up by the book then it's set for super.

To run normal unleaded you need to retard the timing from the book set up by 6 degrees.

I've tried both and found super better.

I had a flat spot when accelerating a few years ago and it went when I changed my fuel injectors but my injectors was 15 years old and done about 150,000 miles.

May be try and check the spray patterns of the injectors and check for leaks.
Worth checking them before paying out for new ones as they are getting expensive now…

If injectors were leaking it should be a pig to start when hot. I run my Gtis on both super and normal unleaded, tescos and branded. I notice very little difference if I'm honest. Not worth the extra they charge imo.

thats asda price super unleaded unleaded
what difference would it make it all comes
from the same source