88 Grand Am, 2.0 Turbo - Couple of Issues

[nuarctable]

Hello again all.

First I want to say thanks!
A few weeks ago, my 88 Grand Am, was running rough sporadically.
Asked a question, and it was diagnosed as the EGR valve.
Got that replaced, and thats now taken care of. So thanks!

Now a few other problems... its always something.

Question #1.
My 2.0 Turbo has 123K miles on it.
I change the oil myself at home. Just did it about 3 weeks ago.
Today at a stop light on my way to work, 55 miles from home, and 1 mile from work, I noticed the oil pressure gauge was ALL over the place! High, Low, normal, it just bounced all over the place for the 2 minutes I was sitting at the stoplight. The RPMs were fine, it sounded good, just the gauge was going crazy. When the light changed, and I took off, the pressure returned to normal.
From what Ive been able to find online, Im leaning towards the oil pressure sending unit? Does that sound like I am on the right path?
If the sending unit goes out before I can get it replaced (most likely this weekend, unless its a simple 20 minute fix), will it hurt anything, or will I just have no oil pressure gauge that works?

Question #2.
Since I changed the EGR valve 2 weeks ago its been running good, no idle problems after driving for 15 minutes, etc.
I noticed last friday, and this morning when I started it up, that at start up it idles rough. Not as bad as it was before I replaced the EGR valve, but not nice and smooth.
Again from what Ive found online, could it be the MAP sensor, or MAF sensor?
Also a possibility might be the Idle Air Control Valve?
Of the 3, which is the more likely culprit?

Thanks for the input everyone, this site has been a HUGE help.
Scott

[J-Ri]

#1-
It does sound like the sending unit or related wiring. Either replace the sensor or check the pressure with a mechanical guage. As cheap as the senders are, I wouldn't even mess around with verifying it on my own car, I'd just replace the sensor. I'm not sure if that particular engine has it, but some engines have an oil bypass valve that lets some of the oil dump back into the pan if the pressure is too high, I'd look into whether your engine has that or not, as they can do the same thing.

#2-
The most likely would be needing a tune-up, but if it's been done recently, I'd say IAC, MAP, then MAF (because unless you tell me you have one, I don't think you do)