New purchase

Hello all-
I just picked up a 78 530i...
The car is very straight and has no rust issues at all
Nice clean interior no rips or stains and every thing works even the A/c...

Here is the deal...the car sat for 2 years...
So I changed the oil/plugs and filters.

I added some injector cleaner to the gas and filled it with premium gas.
it is running out great now, but at idle seems to surge a bit any ideas what it might be?

Also this car is not equiped with a cat in the exhaust, shouldnt it have one?

another question, the motor has 200k on it, on start up it smokes a bit but after about 8-10 min. no smoke not even when you get one it.

Could this be leaky valve guides? if the rings were bad wouldnt it smoke all the time?

ok ...
thanks...