Mystery problem - poor starting when warm any suggestions?

[tino]

Have previously posted that my car would not start at all. In desperation I replaced the fuel pump and filter but that didn't help. Then I re-soldered the contacts on the OVP relay and removed and re-inserted just about any relay I could get my hands on. The car now again starts on the first crank in sub zero weather but frequently when restarting when the engine is warm it starts but labours and shakes as if it's only running on two cylinders and then after a minute or so the engine surges and runs well again. Also have noticed that the cruise control does not work as it should - it engages but then cuts out. Does the cruise and the rough starting have anything in common?
*** Also perhaps a dumb question - where is the cruise control unit?