My Vortec 350 runs great but has lost power when I floor it. I have a 1998 gmc k1500. It has 250k Miles on it but it runs fine. I do my own wrenching and ive changed every fluid and everything besides the fuel pump and spider injection system. I'm very persistent about oil changes and all of the maintenance. Out of no where I've noticed when I step on it it doesn't have any top end power. It just flattens out. There's no check engine light. I'm getting your typical crappy gas mileage around town. It idles fine, starts up fine, everything seems fine except for when you step on it. Any advice to what might be the problem? Is it just getting old? Please, any advice would be much appreciated. Thanks for all of your content.