I went on vacation for a week and the truck sat for about 9 days with out being started, and when I drove it the first time I noticed a slight surge. For example, when I am driving I will hold the rpm steady at about 2500 while accelerating and with out moving my foot I notice the rpm's drop to like 2200 for a second then go right back up. Then is does it again, and again....... It only does it under normal acceleration(to scared to give her hell it has 200K miles). If I am setting still or coasting it does not do it. Any ideas would be appreciated.