3.3 Low RPM Issues

Hello again,
*The Car*
I have a 90 Ciera with a 3.3L (the one with the coil packs up front) with 94K miles on it. I picked it up late winter to use for a work beater after
the weather broke so as to not have to use the 4X4 too much. Right after I got it, the harmonic balancer went kerploohey right next to a garage that works mainly on old cars and when the parts store didn't have one he got a used one from the recycler and replaced it, the belt and the coil sensor. I questioned him on the fact that it seemed to idle a little rough after that and he said it was typical of that motor and not to worry. Only having the car a day or so I could not say that it did not and just lived with it's odd slight 'pomp pomp' as it ran fine outside of that and gave good milage (apprx 24mpg overall and as much as 28 hwy). I changed the plugs, ran some STP Super Concentrate Injector Cleaner through the tank with no change but have been otherwise happy with the way it runs these following 4K miles and with the way it makes a great commuter car expecially in the construction zones where *I idle it a lot* in the jam on the way home.
*The Issue*
Today I used the thing through a fair amount of in-town driving and noticed a few times that it did not start on the first crank but fine the second (uncharacteristic). I then went into a store and when I came out I hit the key and the motor started first try but stalled immediately. I hit it again and it fired and stalled again right away. After a few repeats I tried holding the pedal a little ways down and it started but would not stay running but after a few tries I gunned it a few times and it seemed to run OK. A few minutes later I went to pull from stop sign onto a busy road and the bugger stalled. Popped into neutral and restarted while saying the three word prayer and it ran like it's old self again.
*The Questions*
I'm assuming that the prayer may have helped for that instant, but the language contained likely didn't win any long term fixes from the Big Guy.
Is this a trademark symptom of some sort of regular issue for this car, i.e. does it scream some normal problem? I do most work on my cars but not as much now that only one has a carb... I'm not clueless about cars but not big on Injection motors either.
Is the guy at the garage right about the slightly rough idle being normal on these? I watched as he changed the Crank Sensor and he said the he just rotates it buy hand listening carefully that no fins touch the sensor and that is all there is too it.
I picked up a $20 GM code gizmo appropriate to this year car one day at the parts store, but didn't use it yet as I don't know how. Is this something I can just plug in and have it tell what is wrong or do I need a knowledge higher than a shadetree mechanic (who used to swap motors and parts and such all the time but not so much the last decade or so)?
I can't afford to just start throwing money at an unknown issue, so I'd appreciate any suggestions that might point me to a quick resolution.
Thanks!!!
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symptoms could point in many directions......pull codes and write them down. unhook battery for a few minutes.....recheck for codes before starting (should be none except for #12, meaning you are communicating)............drive awhile and see what codes you get...........some of the codes in there now could be from before you even bought the car..........check back in here with code numbers and someone will desipher them..........kjun
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or stalling when stopping like in high gear could be the transmission lockup solenoid, which failed in many early nineties vintage GM cars. It has nothing to do with rough idling though. I had this happen on a ninety Corsica which started intermittently but failed at a traffic light a short time after the symptom appeared.
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Thanks.
I had a lockup go on an 88 6000 and it was more like driving without a clutch today the engine just petered out in an instant. This just would start and run for maybe 2 seconds and then stall before getting the hand off the key to the shifter to get it out of park... when it stalled (nearly getting me broadsided) it was the first time in gear and there was no shudder or anything... it just quit.
I was hoping it was a classic symptom for the model. I've always driven used cars and done a lot of mechanical work (in fact almost never paid to have anything done no matter the size of job) but have resorted to using mechanics more and more the last ten years or so as I don't have the time or patience anymore. Computerized stuff is new to me... I don't even know where to plug the tester in!
Thanks again.
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Thanks. I was hoping it would sound like some issue characteristic of the model. I'll have to try to get connected in the next day or so and see what it says.
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Ralph D. wrote:

It could be anything. What is your definition of rough idle? It is a 90 degree 6 cylinder. There will always be some vibration. A code reader probably won't do you any good. Check the fuel pressure. Sounds like the pump is intermittent. Or, the crank sensor is old and is intermittent when hot.
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