Rough/low idle

[1lslincoln]

2005 Lincoln Ls Sport. So recently I replaced my locked up motor (spun a bearing) and since iv started consistently driving she’s developed a lurch/shake. It only happens when idling or really slow speed (5mph and below). There’s no codes pertaining to a misfire, only code is for the downstream 02 sensor as I dont have cats. would this cause it? Iv checked just about everything i can think of to no avail (vacuum, coils, motor mounts, etc). Also more iv thought of after the fact, my fuel mileage is pretty bad, about 13mpg on a good day of city driving not beating on it. from what iv read this is pretty low but I have no other CEL besides downstream 02.

 

[MarkEricRoth]

If you find the speed that the shake goes away is increasing, check the fasteners that hold the engine and transmission together, they may be backing out. We had these same symptoms with a Dodge Shadow right after an engine swap. Turned out the garage forgot to torque the engine to the transmission.