My 1996 Pontiac Sunfire has been sitting for over 3 years,is it worth fixing?

Depends on why it was put to pasture. If you have to invest any more than$600.00 to make it road worthy for a year, then no. P.S. scrap metal prices are at a all time high.

It definitely depends on why it has been sitting and where it has been sitting. If you parked it in a field due to engine failure or busted transmission then you may consider donating it for a tax write off, hauling it to the salvage yard, or parting it out. If you parked it in storage and it was not in need of major repair then you should be able to dump the old gas and run new gas with gas line treatment, replace the old plugs and wires, blow out the air filter, and replace the battery if needed. Once the engine has turned over a few times it should start up. Change the oil and filter. Have the transmission fluid and filter changed. Have a diagnostics run on the vehicle and replace items as needed.