Growing up along the C&NW west line to Geneva, I can recall the E units making their "farewell" trips in 1989. However, Metra kept several on hand as reserve units, and during the Mississippi River floods of 1993, Metra E8's piloted Amtrak's California Zephyr from Chicago Union Station to Omaha (they switched from the old Milwaukee Road tracks coming out of Union Station to the C&NW West line at Tower A2 - right by where Metra's Western Ave. stop is on the MILW Dist. West & North lines. - Of course, locomotives could not lead on the C&NW west line unless ATC cab signal equipped (the former C&NW E8's were, Amtrak's F40PH's were not. I don't recall seeing the E8's even being occasionally used after 1993 - if they were, it was very sporadic, and probably ended no later than late '93 or perhaps '94.
As far as the F7's, I do recall seeing them in service on the commuter trains in the summer of 1980. Around 1980 or 1981, RTA (now Metra) took another delivery of F40PH's, which I believe bumped the F7's out of commuter service for good (I at least remember that I suddenly stopped seeing them shortly after the summer of 1980. Hope this helped.