Locking...

Sup guys I own a 96 STS its all good now, got my transmission serviced finally, etc, but the problem is this: Ok, it'll be a regular day, and I'll be driving at around 40mph and all of a sudden, the accelerator locks. It doesn't lock in the way as it is constantly accelerating, it locks and DOESN'T let me accelerate, therefore allowing me to only slow down. Also, sometimes it'll say service emissions test, so is that the problem? We checked the cable, nothings wrong with it, nothing is wrong with the accelerator in general, or so we think. Any ideas?