I recently bought a '97 Ford Ranger from a guy for 'really cheap'. 44 miles later it developed some rowdy rod knock. Being hard headed, I decided to rebuild another engine and install it myself. I had zero experience at such things, but figured 'how hard could this be?'... famous last words. I finished the rebuild and tried to start it today. Before starting it I: 1) disconnected the coil packs and cranked the motor over a few times. 2) Removed the oil filter 3) Cranked it a few times to confirm that oil was pumping and the pump was primed. Then I reconnected everything and cranked the ignition. It started but immediately began to make a loud klank/knock sound. My brother (who was in operating the ignition) cut the ignition off as soon as he heard it. Since I only got a second or two of the sound I wasn't able to locate it or get a good fix on what it really sounded like, aside from it NOT sounding like the rod knock I had before. A few mins later (maybe 5) we cranked it again and it started again. This time, there was no abnormal noise, but the idle was rough. It idled for a few seconds and then died. We tried again and it didn't restart. While it was running oil pressure was normal. I am mostly sure that the wiring is correct and that the vacuum lines are properly connected. I have no idea what it could be at this point. For what its worth, the engine is from a 95 ranger and the ECU in the truck is from a 97.