Hi guys. First post. Having erratic throttle response. It is most pronounced when it is cold but what is happening is that when I accelerate while driving, it will race up to 2500 rpms then back down to 1400. This cycle will continue to occur all the way 30 minutes to work. I am a decent mechanic but had to take it in to have it scanned after I couldn't figure it out. Threw code p0238. I replaced the turbo boost sensor but it is still occurring. Any ideas?