Heads recently replaced new coils etc. But engine has a ticking noise once heated up. Also after about 20 mins of driving oil gauge will flat line upon coming to a stop and then go back to normal upon accelerating. I don’t believe it’s my lifters as the noise doesn’t begin once the truck is started. What can it be? Truck has 197000 miles 5.4 ltr 2002 intake, alternator, pcm, battery, oil pressure sending unit, and torque converter also recently replaced.
Probably worn bearings.
First step is to ask a shop to measure the oil pressure using their calibrated shop gauge. If the oil pressure is going to zero at stop signs, and it is really zero, that is probably what is causing your ticking noise too. Some part inside the engine isn’t getting all the lube it needs. But don’t assume that until you know for certain whether or not you actually have an oil pressure problem. If you want to avoid the going to the shop thing, buy & install another oil pressure sender unit, see if it does the same thing as the current one.
what’s the year and engine size?
It’s a 2002 5.4 ltr