I have a 1988 Chevy K1500 5.7L 350ci TBI truck and it has been acting up here lately it all started about a month ago. I would go to accelerate while going down the road and it would hesitate and bog down. When it happens I can feel a pulse in the gas pedal and hear an audible sound in the engine compartment(it sounds as though the throttle body is slamming back into place as though its not recieving enough gas). The truck DOES NOT act up during idle or when running at low speeds, ONLY WHEN ACCELERATING. And the problem does not happen everytime I drive, it happens here and there.
I have checked the spark plugs and they are a brown color on the tip which tells me that there isn't a rich/lean problem with the plugs. I have also changed the fuel filter, which was FILTHY, after I had gotten the new filter installed I dumped the contents of the fuel filter onto a rag and the contents were a silver/greyish substance. I have not heard of a filter having this color debris in it, so I am wondering what the debris is and what is causing my truck to hesitate?
The hesitation only happens when I press the gas pedal down a good ways to accelerate, like going up a hill or after a stop light when I am trying to reach the speed limit without creeping up to speed. After I changed the fuel filter the truck ran fine when I took it out to test that fix, and I thought that is had fixed it because I would stomp on the gas to put it in high hear and see if it would hesitate and it did not. The next day I went out and the problem had returned, so it doesn't happen all the time, but it happens more than not.
I only run Shell 93 gas in the truck and take very good care of it. I have gotten to a point where I can't figure out what is wrong with out. I have also taken the air filter housing off and started the truck to see if the injectors are giving an equal amount of gas and they are. I have tried to put everything wrong and that I have done in this post that I can think of, if y'all have any more questions feel free to ask. I would appreciate any help at all with this problem! Thank y'all!