that's exactly what happened to mine, i reused my old tb gasket because it looked good, that's not the case, those things will only form a good seal once. it only took 5 minutes to change the gasket, and it only cost 2 dollars from the auto parts store. i drove my car with this problem for a month b/c i didn't think that it could be the tb gasket, after i checked everything else out, i figured it couldn't hurt to try and replace it, so i did and it was fixed, if the problem occured right after you removed the tb, this is definitely your problem......