I am an old school mechanic (points and carb era) and I have a 98 5.2 with 175K on it. Has been pretty well kept and I am second owner and have greatly enjoyed this truck. Was heading down the highway the other day and all of a sudden I lost power and the engine started to make a muffled knocking / thumping (not tinny or metallic) noise if I tried to go much above an idle. NO CEL. Temp fine and Oil pressure in the middle of the guage. Pulled it over into a convenient Checker auto and borrowed their scan tool just to see if there was anything but no codes came up. I then pulled the plugs and while they were out borrowed their compression tester and did a quick comp test. Tested 3 cyls and they were decent but the tester hose popped off so I couldnt finish. Cleaned the plugs and drove the truck home 2 miles at 5-10 mph. Looked it over, couldn't find anything else wrong and after using a stethoscope decided the knock was low in the engine and it ran but felt like it was retarded and it sounded like it had baseballs in the pan. Again no codes. Figured it was FUBARed so I parked it but I need to get her back on the road. I have my 84 3/4 T Ram 4X$ on CL and a guy called to discuss buying it and we got to talking small blocks yadda yadda. Heres were it got interesting. He mentioned that he had had troubles of a similar nature when the Knock Sensor went out on one of his trucks and it was knocking because the computer was misfiring. Now especially since it has great oil pressure and no heating problems I am wondering it it could be something as simple as this? I have also seen a couple of posts regarding the crank sensor on the back of the block. Any thoughts on what this might be? I want to eliminate all the other items before I get busy with putting a new engine it this thing. Thanks for any and all help / advice. David in Cave Creek.