Let's work backwards form 7pm:
90 minutes for US departure with CBP pre-clearance; you are now at 5:30pm.
Limo/taxi from downtown during afternoon rush hour, 45 minute; you are now at 4:45.

Working forward from 1pm:
Deplane and Canadian immigration/customs, 15-30 minutes; 1:30pm
Head downtown, Airport Limo 30 minutes; 2:00pm

For a real foodie meal you are caught between lunch and dinner service.

Where in downtown: what are you interest in sights, museum and food? If you are not looking at a tasting menu you can do a quick lunch bite upon arrival into downtown and another quick pre-dinner bite before leaving.

Like most other question of this type, your flight information would help as to which terminal you land at and depart from.

Since I never transited at YYZ I cannot recommend any left bags service. You can google GTAA or Pearson Airport for airport amenities/maps.