If you can maintain a consistent fps at say 10bps, then it shouldn't be your solenoid. It's most likely that one of your hoses is messed up.
The hoses can be messed up via over pressurizing them or physically damaging them. Also, if the hose is too long, then the hose may be pushed against the barb on the T-Piece, which in turn would offer a much lower resistance to the internal pressure.
I like to make my hosing have a little tension so that when it's all put together, I know that the hosing won't give me any issues that can cause leaks.
Easiest way to check to see if you have a bad/too long of a hose, is unscrew the body and air it up. If there's no leaks, then your hose is most likely too long. If there are leaks, then you have a bad hose.
Also check the oring on the T-Piece of the solenoid. Those are rarely likely to go bad, but they can always have the possibility to get messed up.