Mine's the same way too...
My 82 6.2 sounds like it misfires sometimes at idle,especially right after a cold start--I attribute this to the dead glow plug I cant get out of the frontmost cylinder on the passenger side--I think thats why the right side tailpipe smokes more when its cold too--probably takes a few minites for that cylinder to heat up and properly fire the fuel...at least I hope thats why,I dont have any money for injectors,or the expensive steel lines that will likely break if I disturb them...I havent put many miles on it in the year or so I've owned it,havent changed the fuel filter either

--I would not doubt if the fuel is stale,or has some water in it...
My motor is a junkyard refugee the previous owner installed,then gave up on when he could not get it started!--he claimed it had 80,000 miles,but I think its got more than that on it--maybe a LOT more!

--but it runs decent enough,I'm happy with it so far..
.I have AC G60 glow plugs in mine,got them at autozone,7.99 each(ouch)--dont know how many still work,its started up all winter without plugging it in on 7 of them,but they are already so rusty they look like they've been it it for 10 years

--if I get new ones when theese crap out,I'm not buying AC's-- or Champions either--it had several Champions in it that appeared fresh out of the box,but were dead as doornails.
.I have a manual switch on my glowplugs,and I have to leave them on for what seems like a rather long time when its real cold,,(10-20 seconds)but it always starts up ..
