80TA

I have just replaced the fuel pump with racetronix harness and pump, the fuel filter and got the injectors pro cleaned thru the rail. I have
also swapped out the fuel reg and dialed it in to 44psi line off.

The car for awhile has had a high end problem.It don't want to rev out in third gear. It seems to do ok in the in the first two gears. I know my plugs are original and car has 66,000miles on it. but it did used to run smooth to around 140plus mph. I realize it could be plugs,wires and opti and plan on changing them out next season when do heads,cam,headers and rockers.
I am wondering if my battery is the reason. My scanmaster reads 12.3 or even a bit lower when driving the car around. Does that seem too low? Its otpima red top and has been charged up a lot from running down several times. I think might try gm battery this time around. Hear they are pretty good.

Could the battery make the car run like this. I can't figure out what else would make the car run so lean and buck at high speed. If the opti or plugs or wires are shot wouldn't the car be running rich not leaning out.

Please give me some ideas guys my non lt1 buddies are laughing at my lt1 its going pretty slow and is barely any faster than it was pre mods. I don't have all the mods in my sig installed. Have not installed my headers or cam or 1.6 rockers or my zex kit.I need to fix the leaning out issue before install the nitrous.

Also can you run colder heat range like tr6 if you don't run the nitrous veyr often. Will tr6 foul out in daily mostly city driving?