Bad Idle and Hard Shifting! EGR? Vacuum leak? HELP!

[zawahra]

Hey guys!

Recently my 90 300zx NA has been acting up.

On a cold start, the idle is rough jumping from 1500 rpm and dipping below 500 rpm and then begins to stabilize around 1000 rpm. The transmission shifts hard and delayed especially 1st to 2nd. When the car warms the transmission shifts smoothly. When I first shift into reverse or to drive the rpms dips so low that the car will often stall (only when its cold) so I have to press the gas pedal right away to avoid that. On the highway I'll be moderately accelerating to get to 110 km/hr and it'll sometimes just downshift (Usually at about 80 km/hr.)

I did a ECU diagnostics test and got the error 53 [Exhaust Gas (O2) Sensor Circuit (Right)] I have no check engine light on even though code 53 is supposed to toggle it.

I took a voltmeter to my battery and I am getting a steady 14v (I had alternator issues in the past)

I am thinking it could be a vacuum leak, EGR valve malfunction, a dirty throttle body, or corroded wire(s) ? I am really no expert.

A little background. This is the 5th summer I own this car and I had the engine replaced and transmission rebuilt summer of 2012 because the engine had a crank problem and the transmission was finished (Shifting badly even when warm) at 200,000kms. I only drive this car during the summer months, so I barely put 7000 km on it since. I also checked the transmission fluid and its bright red and clear with no metal filings or dirt. It isn't sticky either.

You guys are my only real hope. I would really appreciate your input, the summer is flying by!

Kenny Z

[ezb57e]

Check everything for air leaks. The hoses are getting to be in pretty bad shape by now on a lot these cars. Even better if you have something that can look at O2 voltages and see if things are lean or what. Spray carb cleaner around while you watch the O2 readings.
The trans will shift differently cold. I wouldn't worry about that right now. The base idle might be too low also.
Its hard to do things well without some data. Get something cheap that will provide a data stream.