I have a '98 Ford Ranger with the 4.0 OHV engine. I recently replaced the spark plug wires and the spark plugs and now the truck makes a strange clicking noise now and then. It doesn't seem to start happening until a minute or so after starting it when it is cold. I don't know what it does if warm because I am not comfortable running it much just in case. The sound it makes sounds similar to the sound that is heard when next to a car in the parking lot that was parked recently. It doesn't make the clicking sound at a fast pace, it is more like a click or two and then around 15-30 seconds later it might do it again. It doesn't seem to want to stall out, but there may be a very light idle up and down, but not enough to make the rpm gauge move up and down. Also, it may take just slightly longer to start. It still starts up on the first try, but the duration seems just a tiny bit longer. It is the first time I changed plugs and wires, but I was being careful. The spark plugs don't wiggle at all and I made sure all the wires clicked. I changed the spark plug wires 1 by 1 to make sure I hooked them up in the correct order. I also put dielectric grease in the very tip inside of the wire boots making sure not to get any anywhere I shouldn't. I tightened the spark plugs tight by hand and then used a ratchet to turn it just a bit more until the resistance was getting strong. Anyone have any idea what this could be? Thanks.