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95 F150 Valve tap and rough start up

My 95 f150 makes a tapping sound when I accelerate. It almost sounds like a clock ticking. I am wondering if this is a valve tap I am hearing. And if so how can I remedy this situation. Also I have noticed that my truck starts up a little rough when it has been sitting for a few hours or more. Could this be that there is something wrong with the wires or what other possibilities are there. Thanks and I appreciate all the responses. Mike

Is this a 4.6 L?

4.9 Liter straight 6

Describe the acceleration a little more, at any speed or between certain speeds? Is this an auto or manual shift? By " It runs a little rough", do you mean rough idle or noisy idle?

The tapping mostly occurs at lower speeds when I accelerate. Once I hit the highway I dont notice it as much. It is an automatic. There really isnt a problem with the idle once the truck starts, it just seems to have a little trouble starting up after sitting for some time.

Do some more searches to see if any technical information is out there in regards to rocker arm or rocker arm pivot issues. Not all valve train noise issues involve lifters leaking down or oil viscosity issues there are engines out there with design or material problems in the valve train. Motor magazine is a great source for this kind of information.