1988 leSabre CHECK ENGINE light seems to come and go as it pleases.
Has weeks where it's off and on constantly...and now as I type I
haven't seen it in a week or more, but inevitably it will come back
on-off-on, etc. Always seems to come back on not at cruising speeds
for the most part, but on decel with little or no load...say when
braking and decel around 30-25 mph. Was told this type of behaviour
was typical of flaky/blocked EGR valve. Any thoughts? Also the thing
pings on accel that only higher-octane seems to alleviate. And i know
that is very often EGR-related. thanks.