Guys - I have an 87' Long Bed 4WD Silverado bone stock - 350 TBI W/700R4- I replaced my plugs last night and they looked VERY ODD to me. There is a dark side and light side - Very prominent and it was on EVERY plug - Here I uploaded videos. But pics are also attached https://www.dropbox.com/sh/eh82mt6slwu29vs/AACEnV7IgmmKcK4pFU3jzTEba?dl=0 Would the timing have something to with 1. lack of power? 2. with the truck temp running low? 3. the odd looking burn on spark plug? Here's a little back info.... When I bought the truck(Sept 2020), it had been siting for since 2003 - (Original owner replaced the drivers side Fuel tank prior to me picking the truck up) After driving it for a few days, occasionally, it would stall when slowly coming to a stop - after it would stall, I'd drop it in park - turn the key and it started back up EVERY-TIME and continue to idle perfect. So far I've completed the following... 1. swapped ALL fluids (complete - front to back- power steering to rear diff) a. new 180 degree thermostat b. replaced all the vacuum lines. 2. plugs, wires, distributor, etc. 3. replaced the passenger side fuel tank w/ accessories - pump, fuel lines etc... 4. Replaced the TBI w/a Holley® p/n 502-6 (670 CFM Two Barrel TBI) (included MAP and IAC) - the truck stopped stalling after replacing the TBI. *** Last week I took a trip to Alabama, and pulled my HARLEY on the trailer - 1. After pulling a trailer on interstate - I don't think I have as much power As I should - 2. My truck was not getting much over 160 degrees (had 180 degree thermostat installed). AND SO -- Last night, I swapped spark plugs to ACDELCO 41-803 gapped @ .035 and switched to a 195 degrees thermostat I pulled the advance connector and checked the timing - With the truck warmed up approx 180 and RPM @ idle (approx 780) the TIMING shows 0 DEGREES - (actually my timing-mark light is approx the width of a nickel to the right of the of the 0 degrees mark) Where should timing be? Can anyone tell me about the burn on the spark plugs? please see attached video and pics below ... Again, I'd like to hear opinions - Would the timing have something to with 1. lack of power? 2. With the truck temp running low? 3. is the burn on spark plug normal? if not, because of timing? Sorry this is so long, I wanted to give as much info as I could - thank you all for your patience.