I just started my 351W after replacing the cam with a CompCams XE. Anyway, it started right up, and I increased the RPMs to 2000 and let it run. At about the 15 minute mark, it began to overheat some, so I shut it down. Question is - is the new cam/lifter system adequately run in? Also, when it started to get hot, it acted like there was some fuel starvation. Vapor lock?