1997 chevrolet pickup

I have a 1997 Chevrolet pickup, the No.5 Spark Plug Builds up and fires to one side, I can drive up to 50 miles per hr and it misses once in a while, I can get up to 60-65 and it does the same. I changed out no.5 Fuel injector and it still misses, I changed out the seals on no 5 valve, I changed out the fuel filter; and the CSFI makes a whistling noise & the sequential fuel box makes a vibration. I can put the old filter back on and it doesn’t whistle or vibrate. I put the new filter back on it whistles and vibrates the sequential fuel box. The trouble light does not come on and tells me to check the engine. Do I need to replace the fuel pump?

Would someone please comment back! I really need some input. Thanks!

Could you try to clarify the problem a little bit? Your description of the problem is not very clear. What do you mean by the spark plug “builds up and fires to one side”? Occasional misfiring can point to a fuel pressure issue, and some of the noises you describe can suggest a failing fuel pump. Fuel pump failures are pretty common on these trucks, so that very well could be all or part of your problem. You do need to check the fuel pressure to get some evidence it needs to be replaced before doing this, though. No sense in just throwing parts at it.

I had similar problem with mine 1997 Chevy. What I found was a wore out distributor gear. These are timed by the computer and they will cross fire if the rotor is between posts. Mine would run fine up till 40 then miss till I hit 60-65. My ck-eng light did not come on also. If you pull yours,mark it and put it back the same as it came out. If you move the crank. You will have to have someone with a scope to reset it. I could only get the gear from the dealer. It was $35.00 2 years ago. I too found a fouled plug.