Engine problems

[busterhymes]

as wobba says check for the tell tale creamy coloured scum inside the oil filler cap and oil floating in coolant tank all signs of a blown head gasket could account for poor running/performance, a good way to confirm would be a compression test

[MatrixGuy]

Checked the oil cap and coolant and it all looks normal

[busterhymes]

you need to look at the simple stuff plugs, leads, distributor cap, rotor arm first, work out if its running on all cylinders. Must be someone who can pop it on a diagnostic to check out the prob
no crap in the coolant oil cap doesnt rule out a blown headgasket again diagnostic would pick it up better imo to get that done then blindly set to and change shit loads of parts

[Coops]

compression test would be a good thing to nosey at aswell