Conditioner usually does not matter regarding grain-raising.
Conditioner is usually used to help make/let the stain apply 'evenly' for woods with absorbtion differences between early-vs-latewood or end-grain vs face/long grain. Almost necessary for such woods as pine, where there is a BIG difference in the wood grain and stain absorbtion and thus tends towards blotchiness.
But you say you used an oil-based stain. Those
usually don't have issues with grain-raising, as grain-raising is more of a problem with water-based products.
You say you applied two coats of an oil-based stain with a brush. Did you rub-off the 'excess' stain after you applied each coat but after it soaked in as desired but before the stain dried?
If not, you probably have a layer of dried stain just glopped onto the surface of the wood. Fix is to resand the wood to get to the desired smoothness and then reapply stain (apply, let soak in, rub/buff off).
For an oil-based stain or varnish, you typically do
NOT use a foam brush, as the petroleum-based solvents in the oil-based product usually are not compatible with foam brushes. Oil-based products are usually applied with a bristle brush (solvents don't really bother the natural hair fibers/bristles).
As I said, usually with stains (oil or water-based), apply (brush or even just a clean lint-free rag), let set/absorb as desired, then rub/buff off. You do not want a layer of stain just glopped onto the surface of the wood.
(I'm thinking furniture/interior stains here, as exterior fence/siding stains are slightly different and usually apply more like a paint and are not rubbed/buffed off).
RTFM.
