First of all, did it run at all before you replaced the fuel? Second, how much have you put it? Third, how long was the car stood?
Fourth, go to your local Toolstation and buy :
https://www.toolstation.com/methylated-spirit/p99550
Add the contents to the fuel tank, start the car and let it run for 5-10 minutes then see what it does.
What gap did you set the plugs to when you did them? Should be 0.65-0.7mm (0.025-0.028")
Sixth, the timing is non-adjustable on that engine.
Seventh, you only have an AAV (Auxiliary Air Valve) you don't have an AICV (Air Idle Control Valve) so the idle speed won't be maintained at 900rpm regardless. The AAV is working, you've proved that.
Eighth, inspect that rubber sock between the throttle body and the fuel distributor for splits, perishing and security - any leaks there will cause your symptoms.
Ninth, buy some Carlube ATF-U, NAPA MV or Dexron III synthetic ATF. Buy a gallon of petrol in a fuel can and add ~1/4-1/3pt (150-200ml) of the ATF to the fuel, replace the lid and give it a shake to mix it then add it to the fuel tank - don't add any more fuel at this stage. Also add about a pint (0.5L) of the ATF to the engine oil.
Start the engine and let it run for 15-20 minutes at idle - don't be tempted to blip the throttle to "test it" - once it's run like this for 15-20 minutes, gradually push down on the accelerator and see how it goes.
Tenth - remove the trim panel under the dash below the steering wheel. Look up and you should see a single ECU for the ignition - there should be a neutral coloured nylon tube ~4mm or 3/16" OD going to it with a short rubber link tube about 25-30mm long (about an inch) to connect it. Make sure this is connected.
Lastly, let us know how you get on. It sounds suspiciously like lack of use combined with condensation in the fuel, dried rubber seals and/or sticking components in the fuel distributor and possibly splits in the air sock between the fuel distributor and throttle body.
Also worth cleaning the PCV system out but that won't normally cause the problems you've got, at least not on a K-Jetronic engine which is what you have there. Just to clarify things, it doesn't have a Lambda-Sond badge on the radiator grille, a catalytic converter and Lambda sensor does it? If so that makes it a KE-Jetronic which increases the fun-factor ten-fold!
(For "fun" read complications!)
Oh yeah, check the air filter is clean as well.
