the old xr3 drove no bother this morning up to a mates garage, it sat for about an hour then i got back in turned her over & it started missing on a the 4th cylinder so i changed that plug as it looked burnt out & changed the leed & gave the distributer a wee sand with sand paper, checked for spark...no problem there but its still missing, she's been ticking away lately & theres a bit of blue smoke so im thinking valve stem seals but can they be so fucked that its filled the cylinder of oil as the plugs a bit oily???

i just need the car running for another week or 2 so a quick fix is needed