Check engine light and bad gas mileage

I have a 91 Accord. The check engine light comes on when I'm going about 65 mph(it doesn't do it every time). After I turn the car off, and restart it, the light does not come back on. Is this something to
be concerned about? Also, my gas mileage has dropped from about 23 mpg to about 17. My car has 177,000 miles. I've replaced the air filter. Any suggestions? thanks, Mark
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Read the code so we can determine where the problem lies.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.