Need some help fixing my last few issues

First this is a 1997 for ranger 4 cylinder 5 speed manual trans mission

I have cleared a few codes by cleaning the egr passages, alot of buildup, map sensor. I have also cleaned the Idle speed speed controller. I do notice that the the thottlebody intake appear to be pulling oil via the hose that comes of the valve cover and connectes into the air intake . I wondering if this is contributing to my problem. Has anyone else seen this and know how to correct this problem.

I am getting some stalling at idle but not alot

I am guessing I will need to replace the IAC and the catalytic conveter, but I would like to see about stopping the oil sucking as I do believe it could be contributing to the problem.

Also if I replace the converter are the onels that they sell on ebay worthwhile to get an just have welded inplace vers the 200.00 Plus OEM replacement