failed my emissions test- high nox

I failed my emission test yesterday on my 94 LT1 z28.

NOX was at 640 vs 480 limit. HC and CO were fine. According to what I have read, high NOX can be caused by high engine temps, EGR malfunction or too much timing. My engine run pretty cool (at about the 1/8 mark while cruising and at the 1/4 mark during stop and go in the summer) so I think I am ok there.

EGR System
Any ideas on how to test the egr system? I took it out after the test and sprayed it with some carb cleaner. It didnt appear to be *that* dirty. I tried pushing down on the plunger part and it moved up and down but there was a bit of resistance - should these things be really easy to move?

Timing
I have a mail order tune and it has the timing advanced... Do you think returning it to stock will be enough to get the NOX down 160 ppm NOX???

Any other suggestions would be greatly appreciated.

WTB - Passenger side t-top (93-02)

After a rather unfortunate incident last night, I am in need of a passenger side t-top for my car. The person I car pool with forgot to latch it down while helping me put the t-top back on the car and it flew off while on the highway! Luckily, it didnt hit anyone but it disintegrated upon impact on the barrier.

Soooo, if you know anyone parting out a car and has a used top for a reasonable price (just bought a house, and am cash poor right now), pls let me know!!!

Thanks
Mike

Coolant Leak

Coolant is leaking between the firewall and the bottom of the black plastic box that the heater hoses are connected to. I opened up the glove compartment and the heater core itself looks fine. Is it difficult to remove the entire plastic box to find out what is leaking?

As a temporarily fix, could I just connect the two heater hoses together? I figure I wont need heat until September....

Stuff for sale from a 2000 Z28

The following parts are OEM from a 2000 Z28 (obo + shipping). Parts were pulled about 10k miles after the car was bought new.

-pan hard rod ($20)
-springs ($40)
-DeCarbon shocks ($50)
-torque arm ($20
-sway bars ($40)
-exhaust manifolds ($20)
-air lid ($20)
-clutch ($75)
-flywheel ($40)
-shifter ($15)
-3.42 gears ($40)
-Steering wheel w/ airbag and radio controls ($100)
-catalytic convertor2 - brand new! ($100)

WTB: lowering springs

Lemme know what you have and how much you want for them!

Mike.