1991 Xr2I Running Rough

[Parentalnightmare]

Hello everyone,

I'm a newbie here, but could do with some help.

When ticking over my XR2i has a slight missfire or rise and fall of the revs of the engine. Also, say I was doing a steady 30mph the car seems to jump slightly back and forth like a learner driver would but not so bad. But acceleration is fine and also decelleration is fine, this only happens when engine is at a constant revs.

Would you think the coil pack is to blame, I've checked the plugs and leads.

Any help would be great.

Thank you.

Paul.