1996 Ford bronco 5.8 . It’s sort of a high speed, high pitched rattling sound. Sounds too thin and toorapid to be lifters or something like that. Sounds more superficial, kind of on the driver side back of the engine. I have checked the PCV valve and it seems to be firmly seated. I have sprayed some starter fluid to see if there were any vacuum leaks and I don’t detect any. I will note that last week it was in the shop and the mechanic lifted the engine to replace the oil pan gasket. Thanks y’all