up till now the beefed up 2.8 has been great the other day started fine drove 5 miles normal then stopped at a light hit the gas and it responded with power loss was misfiring and backfired hard enough to blow a donut out at crossover then continued after having to mat the pedal for it to go with a loss in power and took forever to get up to speed then after was fine while going but did same stunt at every stop. the plugs are still in good shape pulled and cleaned them replaced the wires due to two had melted boots fuel filter was done before i got it and pressure is fine the cap i know has one hairline a half inch long but is taped and sealed no lights came on during this and now randomly it will diesel when shut down for 15 seconds. rather then replace a ton of crap or get irratated and replace the mpfi with the 4bbl intake and heads off my S10's 2.8 thought would ask for suggestions so i dont lay the car up for something simple i overlooked

 

Sounds like a fuel injector is not closing off. Over-rich condition fouling a plug or two matches these two symptoms.
Check injectors, or if unable, compare sparkplugs to each other.
Let us know.

 

ended up being 2 faulty injectors swapped them out in 2's with extra ones from an old build and figured out ones for cylinders 2 and 4 were not closing right.. thanks for the suggestion helped perfectly

 

~SMILE~
You're welcome!