Krazy Ztang 5.0

I have a 1990 FI 347 stroker. My mods that I am aware of are:
-Cold Air Intake 85mm MAF from filter side 75mm on opposite side of MAF
-70mm Edelbrok TB
-Holley Systemax Intake System
-24lb Injectors
-Autolite DBL Platinum Spark Plugs - .40 Gap
-Trick Flow twisted Wedge Aluminum Heads
-MSD 6A Box Ignition Set Up
-MSD SF 8mm Spark Plug Wires and Ign Coil
-Tremec tr3550 Tranny
-Steeda Tri Ax Shifter
-Aeromotive FPR

My fuel pressure is set to 55-60psi to get it to run right and not have any reving problems? If I have it any lower it wont rev up correctly and drives like crap?! I am sure I need to upgrade the injectors, but for the time being I have what I have and don't have a choice but to drive it.. I pulled my plugs and it seems to be running fine, not to lean and not to rich?!

So, my question is, since I only have 24lb injectors on this set up with the possibility of the factory fuel pump and fuel rails, that would be the reason for my fp being so high, right or wrong?

Also have another question?
Here recently I have been noticing that if and when I engine brake, my rear end has a little jar/shake in it? I usually let it rev down some of course b4 doing so, cuz I don't want to be hard on my tranny or engine at all, if it is? Also at around 70-80 mph on the interstate and I let up off the gas I have a shake sounds like its coming from under/around the shifter I can even fill it a little in the shifter, I even went through and tightened up all the bolts on the top half of it, and it still does it, I don't even know if it has different rear gears in it.. It has a SVO cover on it, but of course that doesn't always mean anything?

If you guys can throw me any clues I can look at, it would be more than greatly appreciated..

Thanks,
Krazy

Krazy Ztang 5.0

Hey............
Could anybody please help me out on these questions?
Please????????

Would be much appreciated.....