Mojo88

Ahh, yes, this is great idea about checking the sensors prior to startup. Thanks

Thanks........... I run Marvel Mystery Oil in the gas almost every tank, so should be good that way. Plus, the very first thing I did when it acted up, was to thoroughly clean the MAF (using correct spray cleaner) and I looked inside the throttle body, it was clean. I am gonna change the fuel filter next. Then remove/replace all the plugs (70k miles on them). I was kinda hoping that a big clue was the stumbling only for a minute or so. It really stinks that the P0300 code seems to cover EVERYTHING that could possibly go wrong. Jeesh

I have a 2003 Silverado 1500, with 4.8L 130k miles, very well maintained. It usually runs like new. But then the temps dropped into 30's, and I started getting a bad stumble, but the misfiring only lasts for maybe a minute. Then the engine smooths out and it will run perfect the rest of the day. First few days, no CEL. Then finally it set the CEL and I put my code reader on it and got P0300 (multiple cyl misfire), which is about the worst code to get because it means so many things, LOL. I'm kinda thinking the clue here is that it only acts up for the first minute when cold. Can anyone suggest a likely problem area to look at? Thanks

Great points, thanks, but the fastener store I go to is incredible. They have everything, and they know all about hardness and such. I am normally in the OEM camp though. Thanks again!

Ahh, thanks for the part number. I was hoping to get the thread pitch and length, then I can buy at my local fastener store. That bolt (online) is nothing special, but sells for like $8 per bolt, LOL. Dang...................

'03 Silverado 1500 LS - I am gonna replace the rusted backing plates. There are four big bolts holding them in, each bolt has an 18mm head. But the bolts are super-rusty and I want to order 8 new ones before I start the job. I cannot find them online for some reason. Does anyone know the size of the bolts? Pic below. Thanks!