In normal circumstances, if she's drawing air, the engine will initially rev up, then stumble & die or run very erratically, revving up & down.
I think there may be more than one factor here. All of the above or at least some of the above, sucking air and weak sparks.
Are the plugs in good order?
Are the leads in good order?
Are the coils in good order?
Are the plugs making good contact with the leads and/or coil tips?
And possibly, do you perhaps have a leak at the head gasket? I have seen someone drop something onto the gasket and drop the head on, then bolt it down and ruin the machined surface. It wasn't pretty.
I also did the head on a 2.0 Vectra. Guy bought it, head gasket had been done, lasted 3 months & went again. Got it done again, 3 months and it went again, so he brought it to me. I cleaned up the block, rubbed my finger tips over it and felt the tiniest bump, like a smooth grain of sand near cylinder 4. Rubbed it with sand paper till it was perfect, stuck it back together and 9 months later it was still running when the gearbox went
He gave me the car, I took out the engine & put it in another Vectra, which I ran for 6 months, sold it and 4 years later it was STILL running perfectly. Guy who bought it said it was the best Vectra he'd ever had
The lesson here being, do it right, do it once.... I'm not suggesting you made an arse of it, but things can and do go wrong & you may not even be aware of it
But do the checks and take your time about it. If everything checks out and you suspect the gasket or mating faces, do a compression test.
