happy it runs, but confused!!

Hello everyone, this is my first time on here, and I am happy to be here.

I received my 88 Corolla from a friend, the vehicle is a 5-speed with a two barrell carb. and 144,00 miles. I had to replace the air filter once I got it, and it started running bad at start-up, until it warmed up, then it purred like a kitten. The old air filter was so dirty, it was sucking oil through the intake, now it isn't, and also, before I changed the air filter, it ran fine on a cold start, now it will chug (sounds like firing on 3 cyl.) until it reaches a certain temp. and then runs real smooth after that.

At this time I have not changed any plugs or fuel filter,(if I knew where the filter was!) but that will be the first I will do. Also, when the car runs (chugging) at start, it has a fairly strong gas smell from the exhaust. and when it is warmed up, it has a smell of spray paint fumes from the tailpipe, not the usual exhaust fume smell like others have.

I have ran Sea-Foam through the intake, and the rest in gas tank, as per instructions on can.

I am really confused, but maybe thinking it might be either or both the fuel filter and plugs?