You want a rating. You have been honest, etc. I will submit one. Here is the update. I found TSB 09-003-03 Jeep 4.0 Engine Running Rough No DTC. I hooked up my Carbon Clean, ran MV-4 through the injector fuel rail, almost immediately got DTCs for misfires Cyl 1 and Cyl 6 and rough running -- have done this before (many times in 300k miles) without this DTC. After this, I ran the throttle body cleaner (hook sprayer on TB from a hanging canister using shop air). If this was a crank position sensor, I would not expect Cyl 1 and 6 that are on the same coil of the 3 coil pack rail. Because MV-4 changes the combustion parameters of the air-fuel charge, a "weak" spark could cause this. Misfire vanished when engine was returned to running configuration (fuel pump
feeding injector rail). After carbon cleaning and no obvious misfie, I did a vacuum gauge check on the engine (did not pull plugs to do a shop air leakdown test) -- 18 in at idle, 22 in at higher rpm. Engine does not use oil (Amsoil Signature 10-30, will switch to 0-40 at some point). Found one of the rubber 90 degree elbows, 5/16 in, that connects to the rigid nylon tubes, had a crack -- used weatherstrip adhesive and 3M 88 vinyl tape as temporary fix because the 5/16 in rubber right angle does not seem available (do you know a source? the part is not listed in the Jeep parts catalog (Factory Mopar) -- closest I could find is 53013 632AD that is "everything", not just the elbow). Just road tested. Dash tach shows no wobble at idle in park (scanner does, but only about +/- 10 RPM), and both dash tach and scanner are steady at stop lights (idle in drive). Transfer case is in AWD (not 4LO) postion. Reset MIL; MIL is staying off. *BUT*, the problem is still present -- no DTCs and no MIL. I was watching the scanner traces, my wife was driving at freeway speeds. After engine was warm (based on dash gauge), uphill, off throttle down hill (all freeway speeds 55 MPH or higher), no problem. Suddenly, engine bucked, advance went to 0. Problem went away, and no further systems. No MIL (progress) but still the same ghost. Please see the attached PDF of the traces; I have added a green arrow for the 0 degrees advance. Note that after bucking, that did not show up in the RPMs (but the sample rate may be too low/slow) the 0 degree persisted -- unless again this is a false reading from the scanner application/tool or from a PCM/ECM that did not update. Could this be a PCM or ECM problem? Usually, crank or cam sensor issues have real starting or much less intermittent driveablility issues. There also is a thread that the oil pump drive camshaft synch assembly gets "sticky" (please see image of component) on the 4l without a DTC -- could this be the cause? Do I simply "shotgun"? At any rate, after your next reply, I will file the review.. If the problem does go away after some other part is replaced, may I contact you so that you can add the "fix" to your knowledge base? One more question: assuming proper maintenance (Amsoil AF+4 trans fluid, filter changes, band adjustments, also Amsoil for the transfer case. fluid changes at service manual intervals), no jack rabbit starts, no heavy load pulls, no significant off roading, but routine use, how long does the 42RE last? How long does the NV247 (quad track II AWD/lo range transfer case) last (link belt stretching, friction plates) lAST? Ours has 300k miles, and I will replace (do not have special tools for either box) before on-road failure. I understand no one can predict a failure, but as a rule of thumb when I do the 200k mile service, I change components that I know from experience may not make it to 300k and for which I do not want to pay for an on the road fallure if we are outside auto club tow range (service parts such as filters, hoses, spark plugs, etc., are changed at regular service intervals). Thanks for all your advice.