might wanna mention if its auto or manual
Almost definitely a MAF/intake issue. If he has only had the intake on for 2 months and the problem stated a month ago I would say that could be ruled out (unless he drives insanely high miles), but who knows.most likely its a MAF sensor related issue, have you also serviced your filter recently? it might be overly dirty causing inconsistent airflow.
Just take a tape measure and measure the MAF housing ID and then the stock MAF housing ID. If they are different then the MAF needs to be scaled or you will always have rich and lean conditions. Most just deal with it, but you really shouldn't if you want the intake to actually make a little more power and you want your car to last. Also, the intake itself cannot be tuned, the cars ecu must be tuned.im not exactly sure what the diameter is i will find out, but the injen fits in very different than the stock intake does..also the injen supposedly comes "tuned" already so i never thought different
ID = Inner Diameter, if someone is wonderingJust take a tape measure and measure the MAF housing ID and then the stock MAF housing ID. If they are different then the MAF needs to be scaled or you will always have rich and lean conditions. Most just deal with it, but you really shouldn't if you want the intake to actually make a little more power and you want your car to last. Also, the intake itself cannot be tuned, the cars ecu must be tuned.