I have a early 99 f250 with dp tuner,4" turbo back exhaust, and a DIY intake. Recently i have been experiencing erratic idling problems. pull up to a stop sign and the idle starts to go up and downand then i pulled into the parking lot at work and put the truck in park the idle jumped up to about 1400 rpms just for a second. Also sometimes the throttle feels less responsive when hitting it from a dead stop. Any ideas?