My brothers 2wd has developed a missfire.

Car is fine but as soon as it gets hot it starts running very lumpy. If you remove plug 1 it makes no difference to the way it runs.

Changed plugs and coolant temp sensor so far....

Any ideas......

 

I had similar prob, does it just run lumpy when warm or does it cut out in the end ?
I changed all sensors and checked everything, but in the end it was the fuel pump not giving enough pressure, changed it and the filter and all is fine now.
Mine was as if it was choking when warm.
Good luck mate.
Steve