'87 5K CS TQ CHECK ENGINE light?!?!?!

[Jim & Bev <jazman@accunet.net>]

Well, just when I thought I had everything working properly. (Last week
was a front wheel bearing).  

My car is at 98k miles.

Tonight coming home from work the "Check Engine" light would flash on
briefly when changing gears,  initially while under moderate boost and
4k rpm +.   The manual says could be a problem with low octane fuel, 
knock sensors, or other ignition system problem.  (This is the little
engine symbol with the lightening bolt thru it, not on the autocheck
system, but on it's own dedicated panel light).

I'm using the same 92 octane fuel I have for the last 3 years, from the
same station.  Unless they are selling mis labeled fuel, what could my
problem be?   Any experience out there with this?

jazman
'87 5KCSTQ (soon to celebrate it's 10th birthday)
'93 100CS