Peeved

The first thing I tried was draining fuel tank to remove possible contaminates,no result. I have checked manual to see if filter is servicable , not sure if it has ever been replaced.Wondered if a crack or loose fitting in fuel line was to blame due to the fault occuring when engine is warm but there are no obvious leaks of any kind near motor. Injectors were checked when taken off engine.I do not think the CO levels have been looked at but it does not blow any smoke.Diagnostic results indicated faults with air intake sensor and this was tested with a new one for no result. Thanks all for your replies and ideas.

Have an 04 hilux SR5 3.4l with 170,000 km on the clock that has been a dream until it developed a problem recently. Runs ok when first started, then starts to run rough after warmed up or turned off and restarted.Then it starts to shudder especially at idle, and lacks power,particularly on hills. Have just had plugs and leads replaced,Ignition coils checked and okayed. Cylinder pressures all good,and injectors cleaned [2 were borderline].After this work was done [$750.00 worth] it ran fine for a few days and then back to square one. It is actually a bit worse now in that it used to come and go, meaning after a while on a long trip it would suddenly come good. Now it runs for 5 mins. and the problem comes on and remains until turned off for a length of time. There are no warning lights on at any stage. Not prepared to go to Toyota re.this problem until I win tattslotto due to previous experience, and none of the mechs. I have talked to have a clue, just a matter of elimination and wallet reduction.Hoping for some help please.