93 k1500 4.3 tbi, I'm getting a playing card in the spokes kind of sound when my engine rpm drops through the 1900-1400 range. It sounds valve train related to me. Has anyone had this problem? Any advice/suggestions on how to pinpoint the exact cause and how to fix? Also, I get a valve or lifter tap from #4 cylinder when the engine is cold but once it warms up the tap goes away. Thanks in advance for any replies.