I've done quite a bit of research on the code 1516 now and had a couple friends helping me out..

My question is this : is it driveable with that error code still showing in the mean time until I repair it?

Here is a description that a buddy gave me that helps really well :

Essentially, they are plates between the upper intake and heads, that have ports that allow air down into the heads, but when your throttle position gets to a certain point, like you get on it, butterfly valves, which are also built into the plates, which are actuated by cables/springs, opens up, to let more air in, for more power. There are/were imrc delete plates, probably just the plates with the areas that have the butterfly valves, cut out, but it sounds like no one really makes them anymore. Could probably find some if you really wanted them. They would probably give you a little less torque when driving around normally, but a little more horsepower (someone said 6). I'd leave them alone unless you start having real problems with them.

 

Note : It is a 98 Cobra