Vectra running lumpy/possible misfire

...might this be a hole in the manifold where the 02 sensor used to reside? That would make a spanky-mean bellow...can you look to see if the hole is the same size as an O2 sensor....these things gradually get eaten away as they take the careful measurements of the gasses present in the exhaust...they are important for determining the richness of the air/fuel mix~ this would bring on the CEL (check engine light) because the poor computer would not be able to compute the mix carefully...check for the presence or absence of the 02 sensor...and we will take it from there...thank your for the opportunity to serve you~~judge~

It's not an overly loud exhaust, but i do fear there is a blow at rear/middle and also near the manifold, I've not had a proper look as of yet as it's pitch black at the moment, but I will check in the morning. Thanks Roy.

Well I went out to the car this morning and it won't start, there's a picture coming up on the dashboard of what i can only describe as a steering wheel with an exclamation mark. Been told this may be because it's in "limp" mode. I'm nowhere near a hill and I've got nobody close by with a set of jump leads.