There is most likely your problem......
When you bridge an Amp it has to see 4 Ohms, not less like how you have your sub wired for 2 Ohms
The Amp is probably building up too much heat and going into protection, because your showing the amp a 2 Ohm load when its looking for a 4 Ohm load.
If your running just the 1 DVC with 4 Ohm coils, then you need to do one of the following;
Use only one channel of the Amp and run it at the 2 Ohms (how you have the Sub wired now)
You need to run each coil seperately, 1 to each channel.
The reason they make amps bridgeable is for when you have a SVC 4 Ohm sub, and are unable to drop the resistance down to 2 Ohms to get more power you can combine the channels of the amp, but the resistance has to be 4 Ohms, not less.
Here are some typical specs for a 2 channel amp.
These are from an amp similar to yours from Fosgates site the Punch 500-2.
Rated Power continuous power
125W x 2 @ 4-Ohms RMS
250W x 2 @ 2-Ohms RMS
500W x 1 @ 4-Ohms bridged RMS
92 Bonneville SSEi - Stock - Remaining repairs needed due to neglect by previous owner - ABS/Trac, AC.
Mods so far: Maganflow High flow Cat, Rebuilt */C
Future Mods: Interior swap for Leath, High Output Altenator, Crazy system, Climate Control swap & Custom Exhaust/Intake.
98 Dodge Stratus - Wifes Daily Driver
92 Dodge Shadow - My Winter Beater