TBI Problems... EGR maybe?

I have a 95 LO5 with 102,000 indicated miles. It was rebuilt at 90 and swapped in a slightly larger cam, not by much though. .420 lift on the intake and .443 on the exhaust. Anyway over the past several months it has begun to lose all sorts of power at 3800RPM in 2nd and 3rd gear. While not under load it revs fine straight to limiter. Also in first it will get to 4000 most of the time and shift out with little complaint (maybe a pop on a bad day). I hooked up my laptop and ALDL cable and i have an EGR Fail code, which is understandible becuase my headers have no provision for the EGR. But i had the headers for over a year with no problems at all. If i back off to about 90% throttle (according to DataMaster) there are no signs of the problem at all. I am replacing the engine this summer so it isnt a big deal, just very very annoying. Some days it will run excellent, but when the weather is poor it tends to act up again. At first I thought it might be due to humidity, and that lead me to something with the ignition, however yesterday it was running like poop and it was not real humid, but a storm was coming in and the barometric pressure was way down (dont know what that would have to with anything though). Valve springs were also suggested to me, but it doesn't seem like they would be affected by conditions. ALSO the problem is ALOT worse before the motor warms up. If it is below 150 degress i cant get over 3000rpm in 1st or any gear, but still revs fine with no load. Thanks for reading this far, and I would love any input!

Come on people... help me out here. I need more suggestions. Gonna go for a EGR blockoff plate and see how that helps.

sloppy timing maybe... did you completely rebuild the top end or just drop in the cam?

thought about timing. it is advanced 2 degrees (borrowd a guys timing light at gainesville raceway) but i couldn't get to the bolt to loosen it and move it back. But i really dont think 2 degrees advanced would hurt anything, at least not this bad.

I've decided the block off plate wont really cure anything at WOT, but its like $8 from summit, so i might as well.

Nothing really done to the heads except for new seals and such. Stock springs, I dont remember if I mentioned this, but that has been suggested many a time. I just dont think that weak springs would behave like this. If that is the case though, I will just live with it for another month or two. It'd just be a waste really.

Also there is a lone connector coming out of the harness by the MAP sensor. I thought this was kind of odd, becuase the map sensor is plugged in, and there is no where for this random plug to go. I just figured my truck didn't use it. Can't find it in my repair manual.

Could be a combination of timing, weak springs, cheap fuel, warn lifters, small vacuum leak etc. - everything adding up to an annoying little problem.

Summers almost here though!

how much lift did the stock cam have? how about the duration? what difference did it make as far as engine vaccuum at a given rpm? open valves too high for too long, and you'll kill bottom end power

stock duration is like 194 i think. I'll have to pull out my repair manual (its downstairs in the truck). Can't remember right now, but someone on Fullsize chevy said with a bigger cam than mine makes 18in of vacuum. I knew 12-13 was very low however, from what i understand stock it should be about 20inches. Bottom end is not the problem though. I did find someone that had my exact same problem and worked on it for over i year i think he said. After that year he gave up and traded in on a new truck with an LS1 variant. Doesn't look good for me = ). But the motor isnt staying long like I said, so I can live with it for 3 more months.

New symptom. This morning I hit the remote start as usual but it just turned over a time or two and quit. I get in the truck and try to start it the good ol' fashioned way and it just turned over, but wouldn't fire. I try again, get a little sputter and it quits again. Then I try a last time and pump the gas a little and keep the starter going and it finally starts, but kept acting like it wanted to die again. I held it at about 1500 rpms until it smoothed out and then it ran fine all day. Started great when i got out of class and ran excellent on the way back to my apartment. That was a first!