You just need to practice more, for more hours, more often.
Try to hit at least 30 backhands in a row deeper than service line but in.
At least 50 forehands in a row the same.
Go for at least 50% first serves for practice.
2nd serves, they better be 48 out of 50.
Get someone who can serve to hit to each of your returns, fore, back, into the body. Return at least 3/4 of them deeper than the service line, but IN.
Now you can answer BBob's question. Which stroke is inconsistent?