This is a re-cap of knowledge I gained in a different thread. I'm re-titling and summarizing the problem and solution to make it more useful for future forum-surfers to find and use. After installing a new engine I was having a terrible time setting the timing and getting my engine to run smoothly. Here were my symptoms. 1) When setting base timing (with EIC wire disconnected) it seemed I needed to twist the distributor cap quite advanced (compared to rotor position at #1TDC) to get the base timing to the factory specified 0 deg BTDC. 2) After re-connecting the IEC wire so computer could begin controlling timing, the truck would run TERRIBLE and timing at idle would be 60 deg BTDC plus!! 3) I would then diconnect EIC wire once again to re-check base timing and it would now be 20 degrees advanced even though distributor hadn't moved!! 4) I would then back the base timing down to show 0 deg BTDC, and re-connect the EIC wire, the truck would start up and run, and idle timing seemed correct now about 28 deg BTDC. I would let truck continue to run and warm up. It wouldn't idle perfect, but not too bad. 5) If I shut the truck off after it was warm, then I couldn't get the truck to restart again regardless of distributor position. I check spark with an in-line tester, checked compressrion, all were good and I could smell fuel..so all I could think of was my engine must be flooded. I would have to wait until the next day and start over at step 1! 6) A check of my spark plugs revealed extreme carbon build up for an engine that has only been run 30 minutes total in its entire life. Carbon build up points towards very rich fuel mixture. 7) ECM was throwing codes 15, 33, and 42. Coolant Temp Sensor reading below -28F for 30 seconds, MAP (low vacuum), and Ignition Module not responding. (forgot to mention these in original post..figure they were unrelated!) Solution. It was my coolant temperature sensor (CTS) causing the fuel injectors to run extremely rich at all times. After the truck would warm up, it was actually so rich that the spark plugs couldn't light the charge, and the engine would flood. The rich A/F mixture caused my truck to idle so poorly that manifold vacuum would drop triggering the MAP code..and the ignition code was only there becuase I was disconnecting the EIC wire to set base timing. I thought this was an important lesson, becuase the timing issues had me so focused on ignition system that I never even thought about the Coolant Temp Sensor...I didn't think that was a big deal...not related to anything important. Turns out the coolant temp sensor is main factor determining A/F ratio, cold coolant makes the ECM call for more fuel (This is the choke for a TBI engine) as coolant warms up A/F leans out. Along with MAP sensor, the CTS may be one of the two most important sensors for the ECM to decide how to run the engine. Moral of the story, listen to your codes that your ECM is telling you (and mention them ALL in your forum posts!) and don't get so focused in one area that you fail to think in the big picture about other parts of the system. total cost of solution $11.99 and about 10 minutes of time.