Vauxhall Zafira 1.8 idilling wrong.

Hi everyone,
I've got a Vauxhall Zafira 1.8. 52 plate. I bought it second hand in July this year. It's been lovely to drive until a few weeks ago it started with a misfire. So we changed the spark plugs and replaced the coil pack. Last Friday it became a nightmare to drive. It won't allow any pressure on the engine or it slows right down. My husband thought maybe it was the sensor on the throttle so replaced that. The cars running a bit better after the spark plug replacement but I can't control the revs it does as it likes and there's no accelerator at all. They go up and come down. We are at a loss. We can't drive it and there's no engine management lights at all. The coil pack is new but could it be breaking down?
He's coming in tonight to try and clean the throttle body better apparrently there's a small hole that gets blocked. Vauxhall can't do anything unless they see it we can't get it to them. Plus it's not worth spending 100s and 100s to find out what's wrong. With the age of the car. Thank you for any assistance.