So, we just bought a 2006 SRX, from a used car dealer, with 179,000 miles. on Friday morning.
It is the V6 engine and it does have high miles, but the car is supper clean. I know that doesn't mean much, LOL!
Drove it off the lot and filled the tank up with regular unleaded fuel.
Drove the car all day Friday, on hwy, city streets, cross town and back. car ran great, no issues.
Parked the car over night. Next late morning, drove the car to store, ran great at first, then on the way back, started sputtering, for lack of better word, and idling rough,while stopped at a stop light.
Upon acceleration, car was sputtering (missing) and the CEL, started flashing. it continued this till home, but did not set a solid light.
Took the car for a drive, and was sputtering at first. then shifted it to sport mode and it cleared up,( coincidence, im sure) and ran then ran fine.
I got on the hwy and accelerated hard, drove fast, drove slow, stopped and accelerated from stop, still nothing, car ran great.
Then once I got off the hwy, headed home, it stated again, with blinking light and finally set a solid Cel.
I checked for codes, on my OBD2 reader, but it read zeroes, no code.
I cleared the CEL, so that I could test and get light again to take it somewhere to get codes read.
The next morning I drove the care, to try to set a CEL, and the car ran great again, for a while and then finally started sputtering and flashing cell, but did not set solid, then the engine cleared up and ran fine again and never set any CEL, to be tested or read.
The car has a recent, Passed smog test, within the last few days.

I know it is having a Misfire, but why intermittent?
Why is my reader not reading any codes?
Is it possible that my code reader is out dated or not compatible?
If so , what is a good affordable scanner tool, to replace my reader?

sorry for long winded post, but wanted to include all exact facts.
Without any code, I don't really know where to start looking.