Carb V8 hesitant, holding back, cutting out, difficult to start but then runs

This should be simple for the gurus here.
I am wondering if its simply fuel filter, pump or is it HT electrics / distributor cap.

1. Driving along today it hesitated on acceleration, but after changing to a lower gear at high revs it pulls ok:
2. The idle sounds a bit off, sometimes stopping altogether at lights, by chugging a little then cutting out.
3. Restarting not easy, lots of starter churning, like 10 seconds to 20 seconds. A little choke, it seems to help but too much and there's a backfire.
4. After getting it running, keep the revs up and it pulls away. Its happier in a lower gear than usual, change up too soon and it chugs/holds back and seems like it will cut out.

Tomorrow I plan to change the fuel filter and check the HT leads.
Any other suggestions?

What engine and hold old? Does it have AFM or stepper motor?

When I’ve had something similar in the past with engines equipped with a carburettor/s has been down to mixture, mostly a weak mixture but once or twice a rich mixture. Adjustment of the mixture was a simple fix, as plugs, filters, leads and the carburettor etc etc were 100% and with twins correctly balanced.

I think Discool is on the right line. Depending on which carbs you have, maybe look at popping the tops off and checking the diaphragms are in one piece, if the needles can't rise properly then you will have all sorts of funny running, also check ignition timing.