Hey guys has anyone on here ever seen something like this or run into it themselves? If so please help any input is greatly appreciated. So I just changed my oil and stuff and I've been noticing this since I got the car 3 weeks ago when I rev my engine (automatic ) like just checking the exhaust not and stuff it seems to take a lil bit longer than normal for rpm's to come down like its sluggish it gets up there quickly but then slow on the way down what is this how can I fix it and is it cause for concern? As far as mods go the car has underdrive pulleys,pi manifold, plenum spacer and a dumped exhaust