1990NOS!

I have a 302, I messed up though, it has a stock bottom end and stock block, and everything else built in it "world windsor heads comp valve train, edelbrock intake, zex nitrous, fluidyne radiator, 255 fuel pump the list goes on"....and I think that is what's messing me up.. The problem is I just put a tremec 5 spd in it 3 months ago, and now only when I'm in 4th and 5th gear I hear a clincking kind of like a chattering sound, but when I give it gas, it goes away...WTF!! "someone told me I may of lost a weight a weight on my flywheel..True or not?? I love the tranny don't get me wrong, but I dont know whats up.. Also with the oil pressure, I was having temperature problems, it used to read 160, then I'd go in traffic and of course its going to crawl up there, but not to 190, so I changed the thermostat and found out it already a 180 in it and not a 160, and I put a fail safe in this time, and yeah it gets hot down here, but now at idle my oil pressure is reading like 35-38 and with full throttle its reading 48-50 somewhere in that range....it's kind of worrying me "used to be more"..Also today I took it out and my temp went up to 192 and my oil pressure down to 25 at idle at a light, yeah i went a parking lot and sat there for a while.....What do I do... Some others problems going on is when I stomp it a vibration happens throughout the shifter, and the whole car from about 2500rpms-4000rpms, I was thinking maybe a broken motor mount, I dont know....Somebody please give me ideas/answers or something, I'm lost....or I'm just gonna build a 351 dart iron eagle block with a eagle forged stroker 418 kit, 850 carb, powerglide, keep the same heads, and do a 2 stage wet system, but i want what i can get out of this motor....Thanks for any advice.