Its got to be electrical , right

I changed the head( recond) new gaskets, but it misses on 2,4,&,6 on petrol, runs ok on gas, bit hard to start but once it is hot it is ok, so I have changed plugs leads dissy cap and rotor arm, compressions good, new injectors, tried swaping No1 and 2 injectors, still no joy,, checked wiring diagrame and found that No2-4-6 have a different earth (???) to the others,,,,,,,,,The only thing that I done to any electrial stuff is disconnect the plug at the back of the block, I thought that maybe I'd reconnected it and in the progress had pushed that pin dowm and only that pin was not making contact(16 on the plug white wire with 2 silver swirls) so I jumped from injector to ignition side of the plug, that did not work either
I don't know what else to do, I don't have the cash to go to an auto electrical shop(pensioner)help would be greatly appericated