98 v8 engine noise

I have a v8 when pushing the gas and driving there is a tick tick noise only on driving when i let off gas there is no noise. Also i notice it is not as noticable when the car has been driven for awhile but a faint ticking. the truck has 70k on it. are these engines prone to do this? We have had mustang v8 like this one and never heard this noise when accelerating. there is oil in it. Could it be the valves? Lifters? :confused: any ideas whould be appreciated...

my 1996 v8 explorer also makes this sound and many others too it seems to be a valve related thing but i have been driving with it for 50,000 miles and no probs yet. just something to accept i guess