Hello, 1997 suburban, 5.7 vortex with 345K miles. problem immediately after starting. when the accelerator is pressed for the first time to pull out of a parking space or to drive off, the truck doesn't move and the motor won't rev above about 500 rpms. not enough rpms to engage the automatic transmission clutch and pressing the pedal to the floor doesn't change anything. truck just sits there but doesn't stall. If I let off the gas it immediately corrects itself and then accelerates normally. this has happened on a few rare instances while driving after start-up but always only from idle. Once it goes it drives normally and accelerates fine including passing gear. 7 month old fuel pump and filter, new EGR, and various other tune-up parts. I have a Topdon scanner that says all diagnostic test pass including O2 sensors and multiple others. I've checked up and down for vacuum leaks but don't think that's the problem because it drives fine most of the time. I have scanners, compression and fuel testers, and multiple volt meters. Please don't send me a bunch of basic tests suggested by any AI generated site. Tried them all and no luck. I honestly think this is something simple but can't figure out what it could be. i trust these forums in the hope that someone else has had the exact same problem. I decided to try here before putting it in the shop. Thanks in advance