Help 96 ultra efi issues

have 96ultra has issues. cold start will startup then die. get real bad gas milage at times. 42mpg to 31mpg on the trip to sturgis.lost alot of power in black hills. feels and sounds out of time at times. sometimes get what sounds like kick back thru throttle body. really looking at efi to carb swap. can anyone give some helping ideas

The first places that I would look is for a vacuum leak in the intake manifold, that there is good fuel pressure and your spark is strong (bad plug wires can give you most of the problems you are talking about). Then make sure the engine temp sensor is good. The last place I would then check is that the hot and cold idle settings are right and the voltage on the throttle position sensor is right. The old Mag/Mar induction system for the EFI can be touchy, but once set up properly will run strong. Also make sure that the butterfly shaft in the front of the induction model hasn't cracked where the screws go through it to attach the butterfly plate. But the first most important step is to open the service manual and look up the procedure to set the idle settings.

submariner1 - I have had similar problems with my 98 FLHTCI. I added an Andrews Cam, Programmable Injectors and K&N Air Cleaner. Once completed, I noticed mpg would decrease from about 45 mpg to about 30 mpg while traveling the PA Turnpike from Central PA to Philly. That's a real bummer when the gas tank only holds 4.5 gallons. That means I am stopping about every 125-130 miles to fill up. Would love to see the mpg get back into the 40 mpg range. Tried adjusting airflow and found the best thing is to lay off the throttle a bit. Dropping from 70 mph to 55-60 increases my mpg by at least 10-15%. I have since moved to NC and notice the mpg is again around 40 mpg. That's because I am usually cruising anywhere from 45-60 mph.