[doughboy]

That sounds really bad mate.

I think your problem is the Indy doesn't seem to have clue what he is doing and you have a simple undiagnosed problem which has got worse and worse and possibly led to major issues. Just reading codes and fitting new parts is not the way to fix a sick engine. All these codes being 'reset' they need looking into not just resetting!

Having a regular services doesn't prevent the odd fault. These are complex engines and faults can lead to major problems if left. Unfortunately you buy the car cheap now, but the repair / diagnosis costs are still that of a 40k+ car!

If it is fuel right the way at the tail pipes you're in some deep shit, apart from 4 wrecked CATs.

Creamy colour seems to indicate water/oil emulsion.

Open your oil filler cap, what's the colour in there? Are you losing water?

Worst case could be a headgasket leaking oil and water into a bore causing misfires. Or just oil which is mixing with cold start condensation to make emulsion.

Could be a leaky injector causing flooding and bore wash / ring failure...

Any half decent garage should be checking all these and taking your plugs out for a start.