It sounds like the main pressure pump isn't working or if it is, not well enough.
As the car has been stood for a while, i'd get a couple of gallons of fresh fuel and mix ~200ml synthetic ATF (Carlube ATF-U for preference as i know it works for this) in with the fresh petrol.
Add this to the tank, start the car and get an assistant to keep it running by careful use of the throttle. Meanwhile crawl underneath with a small hammer and give the body of the main fuel pressure pump a few taps - you might actually hear it either start running or speed up.
Not a guaranteed fix but given the low cost and short time involved, well worth trying as it will lubricate the pumps, injectors and distributor (and clean them too), help to remove rust and revive old oil seals and generally help everything start moving again as it should.
Also make sure there are no leaks or possible leaks on the "sock" between the fuel distributor and throttle body. If there are leaks, there isn't always enough airflow through the fuel distributor to move the flap that alters the injection pressure.
Check to make sure you have a good supply to the warm up regulator and that the hole in the bottom of it is clear - if it's blocked it can create a vacuum which reduces the injection pressure, worse still when it's cold!
You may also have a lot of condensation in the tank as it's been stood so long. Assuming you don't have the long range tank (which is actually a separate tank mounted high up on the rear of the back seat broadly speaking) then if the fuel level is at or below 1/4 of a tank, add :
https://www.toolstation.com/methylated-spirit/p99550
Don't mess about with smaller bottles or just adding a bit, it won't work! Needs to be all of it in ~4 gallons of fuel, a 1/4 tank is ~3.5-4.0 gallons so about right. You can if you want add this at the same time as the synthetic ATF to your fuel, save having to do two or three separate adding operations as it can get fiddly with the small amounts. Also you can shake the Jerry can to mix it before adding which helps.
As an aside, also worth checking your air filter isn't blocked, collapsed through damp or whatever, check/clean the inside of the dizzy cap and rotor arm, check/clean the spark plugs and gap them to 0.65mm (usual is 0.7mm but given it might not have the full amount of fuel for idle at the moment, go a smidge tighter to help firing), clean the coil and dizzy cap connections where the HT leads fit in and make sure the PCV system isn't blcoked anywhere and no air leaks on the inlet manifold side from split breather hoses, vac advance lines etc.
Might not be an instant fix but should improve things as time goes on with some improvement almost instantly, even if not to perfect running order.