Intermintent miss/Rough idle after overheating

I have a 1997 GMC Yukon w/5.7l engine, SLE package w/160,000 trouble free miles. During a trip to meet friends in Canada, my wife was driving and noticed the
temp guage was pegged (260 degrees). She woke me up and we limped the truck a half mile off the QEW to a Tim Hortons where I opened the hood and saw steam, not water, blowing out of a crack in the plastic radiator tank next to the upper oil cooler fitting. The engine was HOT. It was pinging and rattling when we shut it down. We went inside the coffee shop to eat lunch and let the truck cool down. When the truck was cool we filled it back up with plain water and started the engine and noticed a limp as if it was missing on one cylinder. We drove the 20 clicks to our destination carefully watching the temp guage.When it came time to drive home, about 250 miles, I added a bottle of barr's leak and made it home stopping to add water as needed. A new dual core radiator solved the overheating problem, but I have been pulling my hair out trying to get the truck to idle like it used to b4 the overheating. The scanner says intermittent miss cyl 4., and I dropped fron 18-19 mpg to 16-17mpg. New plugs, cap, rotor, & wires didn't help. Compression ck shows good and even across all cylinders. At hi idle the engine smooths out and runs better. At cold start it seems to idle better than when it'swarmed up. It doesn't seem to be an ignition problem, could the heat have damaged the fuel spider some how? I read in this group that when the spider leaks it dumps raw fuel into the intake above #4 cylinder. I have always used Mobil 1 in this engine and the oil looked good after the overheating episode. Comments? Ideas? thanks JR
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If this started after the overheat a valve spring could have collapsed, this will not show on a compression test, or a bad hd gasket, there is no quick anser here, all the bases must be checked, a leak down test will show a bad valve or hd gasket but not that weakened spring. This all assumes good injector system and ign also.

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Had a intermittent miss in my '99 Yukon. The distributor was the culprit after changing out the everything else in the ignition system. The plastic base POS one that didn't even make it 100k miles.

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