Looking for someone to help renovate my 1984 Nissan Sunny

Hi, I don't know how mechanical you are or what needs doing but a few ideas - simple ones first :

 start with a half tank of petrol, add a bottle of "petrol magic" or similar (from your local car shop), take the car for a very long fast run (I drove 300 motorway miles to London when I bought a car that was "flat", it was a lot crisper and faster on the way home!)
 is there an owners club you can join and ask for advice?
 look under the bonnet at night when the engine is running - look for sparks around the plugleads.

 remove the distributor cap, check for condensation, fit new cap and rotor arm if they are not 100%. check spark plug leads are decent - renew if not sure 
 give it a service - oil change, air & fuel filter, spark plugs (check what colour the old spark plugs are when you remove them)
 Check ignition timing.
 check valve clearances.
 do a compression test (best done when you change the sparkplugs) - maybe remove the head and ask your local engineering place to recut the valve seats if compression is low.
 I had great results many years ago with a crypton tune by a local garage, not sure if these are still an option?
 book it in for a rolling road session? (check they know about carbs, check prices befoee deciding)

What is the issue with it, exactly?

Pretty easy stuff, I reckon you can sort it have some faith!

+Carb - give it a good clean. This sounds similar to what I've seen which a leak from the gasket between the carb and the intake manifold. Crc/carb clean will tell you. If it runs better, its leaking, replace it. It will run better.

+ If you haven't in a long while give it a birthday. New filters - oil, fuel and air, spark plugs, leads, also as said check distributor - cap, rotor and points.

+ Timing - yup its done with the timing light, shows when the belt should line up with the timing mark.

+Agree with compression test - also advise leak down test - tells you where exactly air is escaping, if it is.

+Tapping and rattling - older engines usually do this to some degree. If its a little tapping its ok. Panic when it sounds like a building site - heavy knocking. Listen with a screwdriver handle you can hear vibrations if its coming from the head or the block. Stephyscope is better.

My TX5 (dohc efi) Ticks like mad because the hydraulic lifters are gummed up. Lifter free and an oil flush and 5,000 km changes help, its quieter but occasionally its rather noticible. Solid lifters need valve adjustments, they get loud when out of spec. The above can still help. The old days mechanics used Auto Trans Fluid to flush an engine.

+Auto box, change the ATF and new filters - it should help it, they don't like gummed up filters and black oil - it kills them.

+Suspension - looseness is likely worn bushings. Jack it up with axle stands, or use a hoist if you can, get under with a pry bar if anything moves excessively its likely the bush has had it. Could be coilovers need a service? They can wear out and may need fresh oil and seals. Especially the cheap ones. Regular struts are throw aways.

I don't think its that bad. I've had a few old carb 323's, Corollas and stuff with between 250 and 300 km's. They may use a little oil, few hundred mills between services. They may tap a little bit but generally they are pretty robust, never had one blow up on me.