You're in luck!
I just replaced the flame trap on my 84 240. You can buy it online at
www.ipdusa.com (assuming you're in the states) for about $1.25+shipping.
It's easy!
Here's how:
Stop the car
Get out
Open up the hood
Find the intake manifold.
Right in the middle is a small rubber hose about 5-7 inches long that leads down. Follow that little hose until you reach the larger plastic thing it's attached to. THE FLAME TRAP IS INSIDE IT. There's also a bigger hose which meets the little hose at the same point. That bigger hose leads to the "beggining" of the intake manifold.
It might seem a bit contorting, but you can remove these things without any tools. Just slip it off and take it apart with your bare hands.
The inside will probably be filled with carbon, oil, and crud. You'll see a little concave plastic "strainer". THAT'S THE FLAME TRAP. Take a small screwdriver and a hammer and tap it out from it's rear. Prying it will never work.

Once you've removed the flame trap, clean out the hoses, etc. as best as you can. put the new $1.25 flame trap in and you've just saved about $200.