oil breather... needed???

i recently put a strut tower brace on my 93 347 stroker motor. as a result i had to take out the oil breather on my valve cover and replace it with a regular cap. i noticed the car makes a gurgling noise after i drive it for a while and shut it off. when i drive it for more than 10 miles and it's warmed it seems to be a little less powerful. is it possible my engine wants to breath some more air in and vent a little??? the breather will not fit where it is unless i take the valve cover off, cut the filler neck down and have someone weld it. if anyone has any experience with this your info. is well apreciated.

oil breather

yes i do have a pcv and it is functioning properly, i had it checked out and it was not gummed up. i am running the stock air pump also but my heads never had the holes drilled in them to make them emissions legal, not sure if that has anything to do with it. i have a windage tray on my t style oil pan, but everything else is where it should be. there is also the line from the valve cover neck going into my throttle body spacer too.