M20b20 holding back on revs and back fire, running ruff.

[ThreeDLee]

M20b20 preface hold back on revs at 3000, then when running holding back at 5000 ish, slight back fire, running lumpy.

Checked spark plugs, rotor arm, distributor cap... Afm looks clean and good on track... No air leaks.

Could it be timing?

Some help would be great.

Thanks.

[E30Gheko]

Petrol pump? I think they have some sort of diaphragm in that can perish. If you put your foot down when driving does it give a lot of lag and force you to change gear?

[ThreeDLee]

Yea seems abit laggy... It's running ok now but still holding back on 5000 revs :/

[E30Gheko]

There are people on here with far more expertise than me, but I had a similar problem on my 325 a few years ago and the petrol pump was goosed.