From what I can tell theres nothing wrong with the intake pipe, I've checked it twice now and can't find anything.
Thanks for your advice Toysrme, how much is a fuel pressure guage, and how hard is it to install. If the fuel injection isn't working properly and the STP doesn't rectify the problem, how much is it gonna cost me for another injector?
I'll replace the fuel filter too, never done that, how much of a mess is that task going to turn out to be?