Misfiring above 80 degrees

[Stringer]

Hi
I have recently replaced a fuel pump relay and an OVP, but i still can't crack a mystery which is driving me insane. The engine starts to misfire in traffic when it goes beyond 79 degress or thereabouts. This last for a few minutes until it comes back down to 79 then it clears. If the car gets really hot and goes up to 82, then it will misfire both on idol and on accelerating for a minute or two, which is making me wonder whether this is fuel related. OR could it be that when the auxilary fan starts, then current is not constant to the fuel pump relay? Are there any particular contacts i should be looking at?
any help appreciated.

many thanks from m in Beirut (and yes, things are getting very hot here so maybe my next post will be about bullet holes)
M

 

[carat 3.6]

Sounds more like an ignition problem M, remind me which bits you've changed already?

 

[Stringer]

New plugs, fuel filter, air filter, 2 new injectors fuel pump relay and OVP. I have also tested the coil with a multimeter (hot) and it seems bang on. You don't seem to want to consider the aux fan though...hmmmm

 

[BlackC55]

Are the dizzy cap and leads ok?

 

[Stringer]

yes, all was required with the cap was to clean the points, same goes with the rotar. Leads are old but i checked them all with a multimeter also - but i think the fact that this problem switches itself on at 80 degrees and above, and then switches itself off when it goes down to 79 probably wouldn't be the leads. just my 10 cents worth,

 

[BlackC55]

I would probably try a set of leads first.