Had overheating problem so renewed heads , gaskets etc, started to misfire, played with it for a while , got fed up with it so left it overnight ,following morning, was turning over but wouldn't kick in , eventully got it started now but still misfiring at 2000 revs ,totally love this car but its doing my head in , x anyone any idea's please x

As you say "heads" I presume it's V8? If so is it Gems or Thor?
Diagnostics would be the best bet but check the connections to the crank sensor and cam sensor.

Plugs leads in the wrong place or crossed over?