hard to start, lacking power

[green monster]

Hi all
been chasing a problem for a fair while now ,hard to start rough idle and sluggish of the lights,, changed sensors and plugs leads filters, fluids, flushed with injector cleaners and almost gave up!!

My mechanic (mate of mine) reckoned it must be a fuel problem, so we put in a new fuel pump ($90) and fixed the problem instantly starts first turn of the key and if i boot it can spin the rear wheels of the lights ,, not that i do tho!!
cam

thaught it was worth mentioning ??

[green monster]

Back to square one !!!!!
still wont idle when ,,,reckon its ignition problem as it does it on both gas and petrol,,,, just wont idle even when cold or hot now ??
but still goes fine when driving, just a problem at low rpm,
cam

[Ridgeback]

Don't have the manual with me, but there is an idle air control valve that from memory is a solenoid that cycles continually but at varying pulse width (Duty cycle air control valve). You can hear it buzzing / ticking away with the engine off and ignition on under certain conditions, located on the throttle body. Have you checked this as it does control idle speed? May be clogged with shite or may be unserviceable.

[Slyone]

head gasket or cracked head?

[Bigbro]

check the muffler i had a similar problem my rear baffle was moving apon acceleration a producing excessive back pressure.