Knock At 700-1200 RPM only when warm

Well Hard To Say. Most People Are Pretty Much Callin Up The Doctor And Sayin Hey My Legs Not Acting Right Whats Wrong With It. Nothing To Go By how Can You Give An Answer. If Its A Knock That Sounds Like More Like A Bearing To Me. Not Being Rude.

Naw, Bearings thud more than anything. I really think it's a fuel quality problem. The only other thing is I need to know if a accessory such as a exhaust pulse valve or egr could cause a knock. Or, does anyone know if center mount cams can tap steadily or bearings tap as a specific cylinder fires? And the only tsb's I am aware of are cool start problems. A knock only at warm idle sounds like somethings loose maybe. Do lt1s have lifters trouble. It might be a lifter not adjusting. But what? Can my tranny or exhaust tap so loud but be quiet otherwise? Could it be a mount? The tranny shifts and hesitates when put from D to R. I checked the plugs and they are worn but ok. I really need an answer from a Chevy expert. PS it doesn't throw a code.
I cleaned up the vacuum leaks, and restarted everything by pulling the battery. And filled up with 91. Poured in mystery oil in case it was lifters
Anyone Really know LT1's
PS You Shouldn't answer unless you have something helpful to say. If the problem was in the data stream or obvious like rod knock Id not ask.