Please forgive me if this has been addressed previously. 2002 GP SE, 175,000. Silver. Has loud knock/tick when engine is started cold or has been turned off for a few minutes. Goes away after a few minutes and then everything sounds great. This is a recent development, within about the last couple of months. No coolant in oil, I checked. I've been all over the internet reading about the noises these engines make. Possibilities seem to be lifters, pistons, intake gaskets, and flex plate. I'm not into guessing games, just want to diagnose it correctly. Please help, or link to relevant threads. Thank you in advance.