1999 chevy blazer LS 4wd auto 167100 miles {black}:shocked:  , The last year of having it started running sluggish and loss of acceleration, i completely changed the vacuum lines, fuel pump, filter, i recently bought all front suspension part everything buy the hub assembly and leaf springs, fuel pressure regulator, TPS, within the last month did a complete throttle body clean with a seafoam spray treatment, the last week i changed battery then the plugs was running a little better, had to wait for the wires a day so i put them on the next day, started the sluggishness again on my way to gas station to fill up. topped off and when i went to pull out (normally didnt get on it) loud knock or clanging sound. i let off the gas to pull over, sound stopped. turned it off checked around, started it back up, no sound but on my way home i couldnt get passed 60, like it slipped timing kind off. next day same thing, hardly normal operating power. pulled into a friends driveway (10 minute trip) got out to open gate and smelled coolant. when i got back in the temp gauge was a little over normal temp. Friend and i checked around until i seen the valve cover was leaking on the front passenger side on the small coolant only chamber, no coolant in my oil. went back home and that night i wanted to see if the plug wires had anything to do with it because it didnt start running like that untill i changed the plugs and then filled up. i was having to flutter the gas to keep in running to have my friend pull one wire at a time to see if it altered the idle or rpm's. no change on any wires when pulled. turned it off, friend went home and that night i wanted to find out the exact location of the coolant leak, at the time i didnt know where it was coming from. so i let it heat up to normal temp, never would over heat, had it run for around 30 minutes before i was satisfied with finding the leaks location. Took the key out and turned her off. went inside to make a glass of tea. About ten minutes later walked outside to see smoke filled cab and smoke coming from under hood windshield side, never seen flames the whole time this was happening, so i ran to get all my work tools out and i didnt want to pop hood to feed the fire is there was one. sprayed water on hood for a minute or so before i thought to pull battery to try and cut all power from it to maybe stop the smoke, plug it was a brand new battery. the whole time i never smelt burning plastic, rubber,   electrical, or coolant just kind off like a burnt rusted metal smell. kind off weird. after turning around to place battery on porch and with in not running and the key out its still smoking but not as much and as i get closer i see either the ignition coil or plug wire glowing orange so i just started soaking her down for a minute or so until it was out. now i have all these parts i bought recently for the suspension, brakes, and a fuel pressure regulator with an idle control valve about $1200 in parts, luckily i didnt make it to purchase the valve cover that night of it doing it. i dont know what happened and it really sucks and very depressing with all the work and money put in it the last year, it was doing so good and was just about to have everything replaced but the motor and trans. only has 167100 miles on her, and all country highway miles, she has never seen traffic a day in her life. my mother owned it  previously. could it have been the plug wire that caused all of this, when i went to go get them, o reilys gave me the wrong one at first. i checked them in their parking lot luckily before i got home, 3 wires were a drastic difference in length with one of the the would of probably dragged the ground. so i went back in to trade them in 2 of them of this set were maybe an eight to maybe a quarter inch difference, as far as i know that is fine, their computer said it fit my make and model, but it said that on the first set i traded back in. and what would cause it to do that with the key out and it not running, and after taking the battery out while it smoking whatever it was was glowing orange for about 30 seconds to a minute with no power going to it. i am attaching pictures to maybe give you a better perspective. any ideas by chance, and i have some brand new in the box parts for sale if you know anyone. LOL. Keep doing what you are doing man your awesome. love the documentaries you provide, the toyota and ford on how the companies were built or my favorite by far. Thanks for your time and reading the novel i just provided,