I have recently bought an 87 xr3i as a bit of a project car. The issue I am having is it intermittently loses power. When full throttle it seems to run fine but when you stop or release revs it shakes, rattles loses power and then cuts out (seems to me like fuel isn't getting through to the engine or something. When having this issue it also back fires and sounds like someone his fired a gun! Had this issue previously but taking it out for a run and one massive back fire seemed to solve it? Wondering if anyone has experienced this problem before? I was thinking it might be crap sat in the bottom of the tank going through to the engine or something to do with the fuel filter?? Any help would be appreciated!