The code 73 is AFR trim valve Upper DC.

It states FTV duty cycle at highLimit (Rich)
Check wire to trim valve, look for hose blockage or off, feel the trim valve while running and you should feel it clicking if you rev the engine it should click faster. we do replace the trim valves alot. they get gummed up and fail.

good luck

Does anyone have the code listing for these lifts. Local dealer will not help with this. Thanks for the help.