Help! I have a 1.6 KA it idles great and seems to run ok - although a little slow, but top end it won't go above 75 it becomes jerky as though it on its limits even though its barely on 4000 rpm any ideas please

Fuel pressure probably need a pump

Could be a number of things. Common faults are coil pack, HT Leads (when did you last change those, Plugs (same again). Fuel filter should be changed regularly as well.

The injectors do fur up but normally cause idle issues and low speed mis-fireing. I would change the fuel filter, leads and plugs first if these haven't been changed for a while and then the coil pack if that hasn't sorted it. I am assuming that the air filter is good as that may need changing as well.

Thanks all I have only recently bought it so am unsure about plugs and leads . There is a definite almost bearing sort of sound when the bonnet is open at start up - disappears after a bit. Would the fuel filters effect all the performance or just the stuttering at top end

The fuel filter will cause stuttering at top end as it is restricting the flow.

The bearing sound is one of three things. Water pump, alternator or Auxilliary Belt Tensioner.

Thanks for your help - I have also noticed that the fault isn't just at top end - it's in any gear and speed and is only there at 4000rpm ( which it won't go above). The engine light then flashes if its pushed a bit more, it's a though there is no more power allowed after 4000revs - Any ideas please

U need read fault more info needed

It does need a code reader putting on it but I would still change your fuel filter, plugs and leads anyway. It may sort it.

This may be a faulty pre exhaust lamba sensor, but I would also change plugs and filter first. Always use NGK plugs.