MGF rough running

Hi all I have been having an issue with the running of my MGF for the last couple of weeks and I haven't managed to get to the bottom of it.
The car starts and idles OK, but as soon as I give it even a little throttle it coughs, splutters then back fires if I hold it down. and makes it un-drivable,
but then in idle it sound very sweet.

I have changes a few things some for new of Ebay some I had spares lying around.
New HT leads.
New dizzy cap and Rotor
new crank sensor, great pain to replace.
replaces the coil with an old one I had lying around.
pulled all the plugs they were all sooty as you'd expect from something miss firing, I cleaned them and put the same ones back.
replaced the throttle sensor with a spare I had lying around.
Checked the Cam belt timing, broke the cam belt cover in the process, every thing seems to line up although I do need a new cam belt as this one appears to be cracking.
pulled the air filter of the throttle body squirted carb cleaner into it, still no good.
Don't think its a blocked breather tube as I pulled one with no difference.

Its leaving me scratching my head wondering what the hell is going on with it.

Anyone experience anything like this before? Could it be a wiring issue? Fuel Issue?

Cheers.
Dan

Hi Dan,
To me, this sounds like crud / waxing in the fuel system. How old is the fuel? If it's getting on a bit, current colder weather will exacerbate the problems using old fuel can create. Bang some high octane fuel into the tank - in my experience Shell is the best.
W

Hi, fuel should ( I think ) be OK as I was using it regularly and mostly it was the shell stuff.
would a fuel regulator problem cause this.

I have been getting an intermediate starting problem which I thought was down to the fuel relay (will not start until relay pack disconnected then reconnected) but I swapped the relay pack for a used one but the issue continued to occur once a month or something like that.

So I'm just wondering has some old wiring causing this?
I don't have access to a pscan scanner.

I've got to a stage where I might just SORN it until the weather is good. save me some money then work on it in the spring.

Cheers.
Dan.

When was the last time the fuel filter was replaced? another possibility is a dying fuel pump

It could be a failed lambda sensor.(O2 sensor)

Hi and welcome to the forum Dan

If you have a coil and leads I am guessing you have a mk1 1.8i non VVC?

James