So Just got the stage 3 1050x (no flex-fuel) kit for my 2015 wrx sti. Currently on the OTS normal wastegate v400 map from cobb, but about to go get it pro tuned. But ever since I got the kit in it had felt slower, the petal feels lazy and the car just does not want to pull as hard. Every time I do a pull it will hit a 10-1 AFR, but at idle it will stay around 14.5 to 14.6. and no cel. And I have noticed occasionally it will want to stumble under load about 4k rpm and if I left of hard it bucks the car about 3 times. Any ideas? MAF? Coil packs? Spark plugs?