Check Engine Light

[David Bokaie <David_Bokaie@NeTpower.com>]

I know that this was discussed a while back but I can not remember if
there was any resolution as far as possible causes.

My car is an 1988, 90 with 110K miles The problem is that the
Check Engine light is flickering and occasionally staying on for seconds.
The light frequently comes on under following condition.


     1= At Night when the head lights are on.  I believe this is not
     just a side effect of the fact that it is dark outside and it is easier
     to see the light.  I believe it could be engine load related...
     2- High speed and letting off the gas.
     3- Climbing a hill
     4- Engine idling and water temp nearing where the aux fan would
     kick in.


I have switched to Cheveron unleaded and have gone thru couple of
bottles techrolin (sp?).  The problem seems to have gotten worst since
I have done this but it may have been its natural degradation.

Could this be related to catalytic converter going bad?

Note that the car is running as strong as it normally does.  Gas mileage is 
the
usual high 20/low 30s.

Thanks,

David