For my Fiance HELP!!!!

Hey all I am taking on a spring break project and need everyones help!!! My fiance's first car is a 1990 300zx A/T N/A w/ 85,000 miles on it (yeah I know she's a keeper) and its her baby. However the previous owner never took care of it and so my gal is starting to have a few problems with it. Here is what I see and what I think needs done. I ask of you to throw in adivce, tips, diagrams, pictures, tools i might need, and anything else. I am referring to an online service manual for help to:

http://300zx-twinturbo.com/cgi-bin/manual.cgi

If you see anything else on the web please let me know.

Already replace:
Alternator
Timing belt

What I see:

Rough idle:
Checking the O2 sensor, PCV Valves, Throttle Position sensor, IAA unit, Fuel injector cleaning, Power balance test if needed, spark plugs if needed, coil replacement if needed
Anyone have a link on how to clean the throttle body? Also whats this I hear about the throttle harness and corrosion?

Hesitation/choppy shifting from stop to 30mph:
Changing the A/T fluid
Need a lot of tips on this one cause I am scared of what I might find!!!

Brake light warning comes on when braking but brake lights are fine:
Checking contact connections.
thats all i can think of

Black (you heard me) brake fluid:
Change brake fluid (no brainer)

Rear Dif oil:
I want to change the oil but all the maunal says is drain and refill(duh). anyone have some tips? Is the drain plug towards the rear? How should I fill it?

Filthy engine bay:
I dont have a pressure washer and I want to clean her up before I start this project.

Chemical disposal:
Where should I dump the A/T fluids, coolant, and brake fluids? Schucks only takes engine oil.

Thanks for all your help guys!!!

Man you have a project on your hands. My guess may be your electrical system. Your EFI wiring harness (engine bay main harness) may be ready to fall apart, bad connections and such. $300 cheapest I've found. I was thinking the PCV's may be at fault. If you are ready to tear down the engine, do this. YANK IT FIRST! Trust me, the VG's are much easier to find the problems when they are out of the bay. I think you may as well go with TT injectors, the ignition coils are only about $16.50 a peice, no problem there, you may as well go aftermarket plugs (NGK triple prongs double-platinum) would be nice too. Denso plugs are about the same. Is there an aftermarket intake system on it? Maybe your MAF was damaged last time the filter was changed (mine was, had to replace it). There can be any number of things that could promote a bad idle with the VG engines... A MANY number of things. Coming from a guy who has torn down many VG's, take this advice, (you sound like you know your shit) but if you have the money, send it to a mechanic man... Much easier, but more money will be gone. Its up to you bro, just dont tear in expecting to find anything... O SHIT I JUST RELIZED SOMETHING! Its a 90 right? Hows the vaccum lines? Are they dry rotted???? Shoot us back with some info. Peace

Um... it sounds like you got it covered more or less... just let me tell you that its a bitch to work on these cars! I have a '90 AT Na also and just had to change the ALT... geez-uz! That sucked! Just wait until you change the Plugs! As for the waste-fluids... dig a hole in your neighbors back-yard and dump away! I won't tell! If this doesn't work-out... I'm sure most shops will take the waste! Good-luck!

O and my engine bay was nasty too... Good old degreaser did the job with wonders. And with those automatic transmission's, may it be the torque converter???? My buddy had the same problem with his Z, and he just left it be, no big problem ever occured. O well, good luck man. Peace

Haha, come on 1viadrft! Guess youve never heard about my project huh? Im down to the heads and lower plenum... DAAAAMMMNN that was a time! O well, haha. Peace

The early 90's Z's Crank Angle Sensor's that if got dirty connectors will cause horrible Idling, it is the mitsubishi part right in front of the engine, if you know what part I am talking about if you get your hand(And watch the fan) and press on the crank angle sensor pretty hard and it stalls out, you know it is dirty, and take it off and get so Connector cleaner.

The CAS hes speaking of. Its on the exhaust cam of the driver side. Peace