Ok i have a 1998 Chevrolet k1500 ,5.7L ,gasoline, 350 cubic inch,SFI, truck and it seems to have some issues recently it has started to die out when i press the gas when its idling from a stop or going from reverse into drive and occasionally the rpm's go up and down from 600-1000 at idle its strange idk what the problem is but it dosent sound like a miss any ideas what this might be?