Slow start and misfire

Hi there

As this is my first post i would like to say hello to everyone! I've grown up with my dad always having a mk1 gti and its definitely rubbed off on me as i love them too! I have acquired a 89 mk1 gti convertible, problem is it has a few little problems.
It is very slow starting up, have to turn the key for quite a while until it fires up but once it does it seems to tick over ok. Is this a starter motor issue?
It also has an intermittent misfire which seems to come on when you accelerate hard at about 3k revs, almost like no fuel is going in at all. I wondered is there is a blockage somewhere in the breather pipes stopping the the fuel injector unit to cease working? Does this sound about right?
Any help would be great!!Cheers
Alex

A few things really.

I had this issue along with another Member.
His issue was down to HT leads. But can be also dizzy cap, rotor arm or timing is out.

Mine was the idle air screw, which has a rubber O ring which was flat and split which was allowing idle speed to run faster. Plus under load pulling more air past the screw. I was advised also to put higher octane fuel in. These cars can run on lower RON petrol, but needs the timing set to that. I put some Shell V super plus and a new idle air screw seal, took the idle to 900 RPM and know it runs lovely.
Lazy starter can be an issue. but the old Negative earth strap can cause problems as they get older they get dirty and increase resistance.

Also check the rubber pipes for splits and perishing.

Hey
Yeah I will have a check round the pipes see if anything is a miss.
The idle speed is running high. It is running constantly at 2k revs. Could this be a cause? 

with engine on leave to warm up.
Look where the throttle cable goes, it goes to a lever as in the picture, just under there you can see the brass 7mm idle air valve screw. Turn this clockwise to wind in till revs drop to about 900 RPM. Try this and have a drive.
I also put higher octane fuel in, but replaced the O ring.

Like I say check the HT leads, pipes, dizzy rotor arm etc.
Plus the timing could be out.
It's all experiment really. Dizzy caps, rotor arms are not dear..

Awesome thanks for that I will try it later. 
The ht leads and stuff all look band new but ill make sure they are all connected up. 
Sorry to sound stupid, but coz its fuel injected will there be a dizzy and rotor arm? Lol. 

Yes just follow the leads back from the spark plugs they all go to the dizzy. One from the centre goes to the coil. 

Let us know your findings please.

Hey
Wound the revs back down a bit and now she starts up better but the misfire is now not only whiles driving but appears to be on idle.
Do I have to adjust the fuel intake using the Allen key? 
Cheers

Have you tried higher octane fuel like shell V super yet?

I would get some in and see how it runs then. Plus the timing may need setting up.

You can also get supermarket petrol in higher RON rating, Sainsbury super 97RON, Tesco Momentum99 which is 99RON. These cars engine were built/designed when 4 star leaded was about which was 98RON, they don't need the lead in the petrol but the high rated petrol to run at there best…