I was driving my vehicle today for about 10-15 minutes and I noticed that my engine felt like it was running differently. I could feel vibrations through my car, my rpm's were definatly being lowered, and it felt like someone was pumping the breaks slightly 2-3x every second or so. It was a weird feeling, there were no unusual noises comming from the engine though. It definatly felt like there was additional friction, like someone had poured molasses into the engine. Any ideas?