I just installed 38 lb injectors with a 76 mm maf with the 38lb sampling tube, my car would studder real bad under any load, took it to a shop and they said it was running dangerously lean, they put the old maf back in and it runs 99% better but I still have the 38 lb injectors, what else could it be and how is the car running ok with the stock maf and 38 lb injectors?