I just built a 5.9 (gas) engine with 11.5:1 compression to be run on E85. I installed it into my 97 Ram 1500, 4wd, 5 spd truck that had a 5.2 engine. The engine I built was a junker and I don't know it's origins, but the only thing i used from it was the block. I started with new head castings and pretty much everything else. I used the flwheel from the 5.2 engine that was the original engine in the truck. I marked it at the #1 firing position so that it would be in the same relative position on the 5.9 engine. I used the crank sensor and the distributor from the 5.2 so that everything would be the same. The 5.2 was running fine. The company that makes the conversion box for E85 reccomends using a 50-50 mix of gasoline and E-85 to begin with. The misfire was there from the time I started the engine. I checked with the converter box tech and he said it should have gone away after just a few miles so I took the conversion box off and still had the same problem. I had new plug wires , plugs, cap , rotor, etc. I was getting 1391, 300, 301, 302, 304 , 307 ,308 and 320 codes. I replaced the crank pos sensor and the cam sensor( dist PU). No improvement. Someone ( I think from this forum) suggested routing the wires according to a service bulletin that had been issued for a misfiring or cross firing problem. I did that and it helped, but the problem was still there. Now I get 1391 and 1398 codes consistently and sometimes a 320 code. Since both refer to crank pos signal I just ordered a CA sensor from the dealer since I have heard of problems with the aftermarket sensors. The truck runs pretty good under load or accelerating, but it misfires at a steady speed on level ground. If i go up a hill it does fine going up, but misfires badly when I let off going down hill. The fuel pump is new. I cleaned the rails and injectors when I had the engine out. The plenum plate has a new gasket properly installed and torqued. The vacumn is rock steady with 18 at idle. I am going to put the old crank sensor back on this afternoon and see what happens. The E85 converter box can be adjusted to lean or richen and it doesn't seem to make much difference. Any ideas would be appreciated. Thanks