My carby TP has taken to running rough with power loss when asked to accelerate in upper gears. Feels like a lean mixture. Starts well and has no problem accelerating in lower gears. Replaced dist cap and internals, leads and plugs but no improvement apparent. No sign of perished hoses on pc gear. Can anyone assist, please.

Compression test might be a good idea.
Does it seem like one cylinder missing??
Double check ignition timing also. Vee

to running rough with power loss when asked to accelerate in upper gears

why only 4th and 5 th
at a particular rev range--- does it rev up and hold all revs in neutral ?

done leads and plugs

no vac leaks -

you were asking about fitting a TR carby dissy-- did that go ahead ?

did you time it to 13 deg and idle at about 800 rpm ?

Taba,
I did a bit of work on my old TP carby wagon. Lots of the stuff is posted here. I found lots of small things particularly with the vacuum controls.
Its been a while since I did the work and now have a TW on gas.
Just search for my threads.
Hope this helps.

Thanks everyone for the advice. Replaced the vacuum unit on the TR distributor with a new one (rebuild I think) and now all is well again with improved performance.