I have a 2002 ford ranger with a 3.0L and it has 155,000 miles on it. It has ran perfect until yesterday. I drove it to work and it felt fine, but I noticed twice that the "check gauge" light flashed very quickly. It was running fine, so I thought nothing of it. After work I hopped in my truck and it would sputter whenever I bogged the engine down (its a manual tranny). When going down the highway in OD and going up a big hill the engine would bog down a little (thats normal of course), but when it boggs the engine surges or something. I drove it home and again this morning it did the same, so after work I went to the parts house and got new plugs, wires and a new fuel filter. I changed them all and it might have helped a litlle, but its still there. I did notice that the "check gauge" light flashed once during my test drive after replacing the parts. I never have seen a "check engine" light come on. The plugs had a whittish, almost powder on them (lean), but otherwise looked okay. Any ideas? Its obviously not running right, but nothing is causing the check engine light to come on. At at higher rpms or flooring it, it sometimes surges, but generally it runs pretty good.