I have a 1998 f-150 2wd 4.6L. For the past year ive noticed that when driving at highway speeds under normal driving things are good, BUT when you give it some gas you can hear what sounds like the lifters or something ratteling or ticking. Doesnt seem to affect power, but sounds awful . Just had a tune up, fuel system cleaned and new fuel filter a few weeks ago. Truck has @111,000 miles. 93 Octane gas seems to make it quiter and less sometimes it goes away. ANY IDEAS???????????

 

Do a search for "Pinging" and that should give you some ideas. It could be the the EGR valve port plugged. I was having a similar problem with my 1998 4x4. I ran some Sea Foam through it and it quietened mine down. I never had to do anything else to mine.

 

i have the same problem, mine isnt to loud but i can hear it with the stereo turned down, ill have to do a search for where the egr valve is lol and try that

 

Something tells me it could actually be your manifold. Our 00 has a few of the studs broke off and you can hear it tick just as you describe. Very annoying but sounds like its nothing uncommon for the bolts to be rusted off the manifold causeing it to tick.