It's my brothers 98 T/A 5.7 LS. It must have lived a rough life. My brother replaced the oil pump after the pressure bottomed out. When the pan was dropped it was determined that the cause was sludge an the pan and bottom end of the motor was cleaned out good and a LS6 oil pump(increased volume) is used. All is well and he changes the oil several times and no pressure drops. He decides to do a cam swap and a custom tune. The guy pulls the valve covers to change the springs and it's a mess. The heads are cleaned and he brings it home. On the way home pressure drops from 60psi to a tick below 40 and the lifters chatter. He limps it on towards his house. Pressure returns and he romps on it and all is well. He's just freaking out because all the money he's dropped in it with cam, tune, headers, ls6 intake, and stall convertor. He asked me to help him flush it and I've been trying to find a good product for it. The sludge should mostly be gone after the bottom end and heads have been clean but apparently there is small particles that need to be dissolved and flushed out.
Bill