95 ef 6 cyl surges under load and changes idle.need help

[walk2148]

hi all
my 95 ef 6 clinder, surges under load, changes idle speed at the lights, and generally runs like a bag of ИИИИ. the engine empties the coolant reservior every three days with no apparant leaks, and it can run quite warm/hot at times.
i have done injectors, fuel and air filters, had electrics checked, and checked for air/fuel leaks all over. i have replaced radiator and all hoses.it does not use any oil, and the oil is always clean and has no discolouring of any kind.

three mechanics including my local ford dealer have checked it and all have diagnosed different things, from stuffed head gasket, to sucking too much air (but wouldnt say where from). and the last said it was an overheating problem.
if anyone may have a good suggestion, other than burning it, i would appreciate a guess, to avoid spending more money on poor diagnosis, or replacing parts that dont need it.
regards bazz