1975 1.8 on twin carbs running poorly Options

[dt4]

My car is now registered over in the UK so I can enjoy it at long last, I took it out today for the first time other than the short drive to the MOT centre last month

It drove OK to a point but I noticed it was very slow to respond once in 4th gear, it felt very flat and not at all keen to pick up speed
If I shifted from 3rd to 4th at around 30mph / 3500rpm it was sluggish and a just over 30mph in 4th it felt like it was in the wrong gear and needed to down shift back to 3rd

on the hills it soon ran out of grunt and I was having to down shift from 4th to 3rd and even 2nd to get it to rev again and build speed
Setting off on a hill I had to really increase revs in 1st before shifting into 2nd otherwise it would bog down and feel like it was stalling

thoughts:
fuel?
timing?
other?

thank you
David

[dt4]

As the weather has been reasonable (dry) this weekend I decided to just drive it and see how it went, there is 5 months of crap weather when i can do garage work.

went for the drive the shit out of approach, the Italian tune up seemed the right thing to do

On both days it took a fair bit of starting and it really didnt pull well when first setting of.
It was very sluggish and wouldnt rev if I put my foot hard on the accelerator, I had to feather the throttle and find a sweet spot where it would pick up revs and speed.

On both days once it got going and after maybe a mile or so it was fine, it pulled well and accelerated strongly.

I drove it pretty hard for an hour or so on both days, managing to find some quiet back roads and was able to give it a good work out.
It does feel a bit squirrely at the back if pressed a little bit in the corners, more the right hand side rear than the left but thats for another day

the main issue is with the poor running when cold / at initial start up

If it had fuel injection i would think it was the cold start injector but as its carbs and doesnt have a choke for initial start up I am looking for suggestions

cheers