My car has no power and hard to accelerate at a full stop need to shift to drive 1 to have power but mechanic can't find any diagnosis code?

What is your question?

It has been on and off for a year now and I went to several mechanics some change the transmission oil and filter and one mechanic even told me he changed the solenoid but still the symptoms keeps coming back sometimes it is good for months sometimes for few days only, Now mechanic suspected a bad ignition switch. spend more than 500 bucks already and no fix seems happening.

What makes this problem better or worse?

no power and hard to accelerate on full stop

How long has your 2004 Chevrolet Trailblazer had this problem?

few months