i have a 6.5 and i took it to a shop to get it diagnosed because it constantly mad a bloop noise.they told me it was a stuck lifter.so i bought new heads and lifters and that didnt solve the problem.the noise has no effect on anything except annoy the crap out of me.any suggestions to what it is?the noise stopa when i put my hand over the air intake tube but starts again after i lift my hand off it