My truck is bogging

I have a 1990 B2200 FI motor seems to bog on me at first I thought it was a vacuum problem but then I pulled 2 of my spark plugs and they were as black as can be would this make my truck idle rough and want to bog out on me or is there a bigger problem that I am going to have to deal with please any suggestions would be helpful thank you Keith R

well if you plugs are black i suggest replacing them and see if the issue was just extremely old plugs. Check them within a few days to see if they are black again. were all of the plugs back or just the two?

When some one mentions bogging i would suggest doing the fuel filter at the back of the truck. it costs under 10 dollars to do yourself.

I only checked the 2 plugs and they were black but they dont look that old if you look at them from the top and thank you I will check the fuel filter and the pump to while Im at it