towing with 4cyl engine?

I was wondering if it is possible to tow a 19 foot fiberglass boat behind a 4runner with a 4cyl engine. Would it be totally underpowered, or should I opt for the 6 and bite the bullet on the gas. I don't tow very often.
Thanks
TONY

I don't think you should tow anything with an old 4cyl 4Runner, but if you are willing to downshift alot and go slow you can do it. Don't forget, your max towing rating is 3500 lbs with a fresh engine and new suspension.