johnny m

i was wondering if any one can help i was thrashing my 92 wrx quite hard on sunday when the check engine light came on i popped the bonnet and noticed my dump valve was open while it was ticking over and the revs were eratic up and down then check engine light went out and every thing seemed ok again the revs were normal but the dump valve was still open it is a baileys dump valve and seems to still be working only it is open when its ticking over when i shut the engine off it closes .can anyone help