2000 Chevy Tahoe 5.7L Vortec Misfire

My 2000 LTD Tahoe 5.7L Vortec Recently started missing at about 4,000 RPM. At idle in neutral or park the motor Revs up fine with no misfire. It will sustain a high rev at 4,000 rpms with no miss. I recently checked compresion at the dealer and all 8 cylinders are fine. I had all the valve springs replaced at the dealer and double checked after I found my valve cover was not properly seated. The only thing I have done that has helped is I replaced the fuel filter and used B-12 fuel injection cleaner, when that was done the mis wasnt as evident ''ie'' the power loss wasnt that bad at all but still some power loss. I had all injectors tested and grounds, maybe a bad ground but to no avail. The fuel pressure is great fuel pump is new and running very well, no more hard starts it fires right up. Heck I wouldnt ever know it misfired at high rpm if I hadnt passed another car on the freeway. I never tow anything with my tahoe I never street race it either. There are only a few things I can think of that would cause this random misfire. Possible oxygen sensors bad, knock sensor is a possibility, or cam position sensor. I have scanned it and so has the dealer but all I ever get is a random misfire. About a month before the misfire I changed wires and plugs Dist Cap and rotor and it ran great for about 4 weeks. Can you guys help give me any insight? Oh one more thing, I checked the coil last night and voltage is fine at low RPM I didnt check it at High RPM but it is about 8 months old MSD Coil.

Edit: I completely forgot about this but about 6 months ago I removed my air filter and sprayed throttle cleaner down my cold air intake. Yes I was bored and I was drinking beer. My truck didnt run right or idle well at all after that, but I forgot completly about the MAS. I removed it and wiped it down and rinsed it with purified water, and let it dry.

Update: Ok I just cleaned the MAS and reinstalled took the tahoe on a test drive and had a misfire at about 4,000 rpm. On the way back to the house I again did the same test drive and no misfire at all. Well thinking that maybe I just didnt realize that it happend I decided to go on one more run down the street, well on the way out sure enough there was a misfire but I lost little power when this happend. On the way back no misfire at all. Oh and by the way I reset the computer error code, and the check engine light wont come on when it misfired but before I touched the MAF I could get the check engine light to come on everytime it misfired. Maybe the fuel injection cleaner is helping im still on the same tank of gas but im now about half a tank, when I put the injection cleaner in I had a little over three quarters. I still have no clue what the heck is wrong with the tahoe, im mentally exhausted from trying to figure it out, and right now im kinda tired of putting money into it. By no means will I sell it but maybe ill park it till I get some good sound advise or wait and buy parts one at a time so my wallet doesnt sting as badly. Oh well I gues im driven the inlaws car till the tahoe isnt a pain in my A*& anymore. If you can help that would be great or if anyone out there reads this post please give me your two cents, heck call me a dumbA& too if you like. Thanks.

I followed your tip. Less than 20 minutes of driving with the Chevron Techron fuel additive on back roads and freeway with lots of stop and go's the miss slowed down and my power picked up alot. Seriously I have only had a couple of misses since and the two I have had werent all that bad at all, heck no one else would have noticed it my wife didnt and she drives it alot also. I had almost no power loss the two seperate times it missed and I havent even used 1/4 of the half tank you mentioned I should use with the additive.

Edit: I just drove for over an hour city and freeway and no miss at all and sooo much power I dont even remember my tahoe having this much power. I think your dead on about the dang poppets, ive orderd the spider already from a chevy parts dealer not to far from me. Im getting a great discount too. Thank you so much for your advise, I mean it you truly helped save me alot of head banging against the wall! =)

Oh and im sorry to say boss but I used Jegs 8.5mm Wires that are application specific for my Tahoe, I get new ones wonce a year now for about 8 years and I love them I replace tehm and plugs and filters wonce a year so I can pay attention to it and keep it tip top as possible. The stock Delco wires worked very well but I used to get a wistle in the Radio when I had the volume low while driving in town. I switched to the 8.5 mm from jegs and never looked back. I use Ac Delco plugs cap and rotor though there the best brand and quality for your money on the market with out a doubt, Ac Delco parts to me me mean quality pure and simple.