Riding back from a rally last fall my throttle failed after about 200 miles. At the time I thought the throttle wire had broken and just needed a replacement. So the mechanic replaced the throttle assy and it worked... for about 200 miles. And it became unresponsive again. I took it back to him and he unplugged everything and greased and replugged all the wires he thought were suspicious. He said I needed a new ECM and thought that would fix the problem.
This past weekend I rode around town trying to get the problem to happen again. And it did. After riding about an hour, the throttle would fail every couple of miles. I pulled over and switched off and on until the throttle would come back, then ride a few miles and do it again.
After reading these forums a bit I learned how to pull the codes and decipher what was wrong, here's what I get:

P-1353 - Front cylinder no combustion
P-1511 - Throttle actuator power management failure
P-2135 - TPS correlation error
Part number-32933-08

When the throttle quits it sounds like the engine goes into safe mode, like when it overheats, running on one cylinder.

So my question is: What do I replace? the throttle actuator? I've seen a lot of 1511 error codes here for Road Kings.

And help is appreciated.

 

Have you checked the the harness plug at the throttle body ? I have heard of moisture getting in that connecter at the throttle body causing similar problems.
I had a similar problem with my tbw I found a poor connection in the molex connecter behind the fairing.

 

^^^^^That. Disconnect and reconnect the servo motor plug several times.( it's in the 9oclock position behind throttle body). The pins will chaffe inside the connector and lose signal. You can also add a dab of dielectric grease to the pins. This may not be your problem but it's a very good place to start.

2010 Limited with some stuff