I went for a blast yesterday and suffered a mis fire problem. I have a standard pinto injection setup on my car. It was fine for about an hour and then started to misfire under acceleration. The misfire was almost like a momentary loss of all power and then it coughed and picked up as normal.
My first thought was to clean the inline fuel filter which to be fair was a bit dirty.
Do i need to look out for anything else.
Thanks Rich

yeah sounds like fuel starvation, is your pump up to the job? clean all filters and injectors

Check your fuel tank for sealant debris as this can sometimes block the pickup pipe and move away only to do it again at another time.

Mike

vacuum in tank? have you got a breather fitted? do you have a fuel pressure gauge? if so can you see the pressure at the fuel rail?
do you have a swirl pot? how is it fed and are you sure it isnt running low when you have to issue?

I have had this sort of problem for a long time and still havent got to the bottom of it
I fitted an oil pressure sender to my fuel rail and connected it to my oil pressure gauge via a toggle switch so i can flick between the two while driving... i have found that i can spot the pressure starting to fall off after about 50-80 miles at which point i pull over and give it 10 minutes then its fine again.....

I am now thinking that my standard sierra hp fuel pump needs replacing.....

How much fuel was in the tank when started to get the problem ?

there was about half a tank of fuel on board when i got back so not low on fuel. I dont have a fuel pressure gauge fitted.
The fuel pump is a bosch electrical pump mounted below the tank.
I will check out the other suggestions and see what happens although i wont be taking it out today as its pouring with rain now.