Plugs, misfire and gas tank gauge...

Hi all,

1) Had a bad oil leak around the cam covers - wanted to check where it came from so cleaned them with engine cleaner and carefully (so I thought) used a pressure cold water washer, trying to avoid electrics - whilst the engine was running. Found the leak (breather/separator seals had gone), but now have a misfire ranging from annoying and occasional to downright dangerous!

Have taken all the injector connections off, put WD40 on and copper grease onto connections. Took all the coil packs off, cleaned them, WD40 (especially where the wires go in). Put WD40 on the connectors at the end of the coil packs - where they join the main loom at the back of the engine - didn't have time to take them off. Improved, but not cured. Any thoughts?

Seems to be ok until the engine warms up, then the fun starts. Usually at idle or on light loads in top - when it starts misfiring, if I change manually to 3rd, it goes away.

2) What plugs should I put in? I want to eliminate these from the equation - and they haven't been changed in 100,000 miles anyway.

3) When I fill the tank with fuel, gauge goes to full. When driving the gauge fluctuates very slowly down to empty then back to arbitrary points on the gauge. Seems to do this more when the weather is hot - or is that just me imagining things?!! Is this a voltage regulator and if so I assume that it is somewhere inaccessible! Or something simple like a blocked breather (as if anything would be that simple....!).

Thanks in advance

Tony