4% is a big number for such a large economy. The fact he hit 3% is an achievement.
It's much easier to achieve if you cut down your expenses, which neither party seems willing to do.
His economy isn't doing nearly as well in GDP growith, in job creation, or in wage growth, as the Obama economy. Trump promised "jobs on steriods", and that's not happening. He promises workers a $4000 a year raise from the corporate tax cuts, and that's not happening.
You want to achieve growth, raise wages. There's a lot of pent up demand among working Americans and the middle class, but they lack the money to act on that demand. All of the sluggishness with growth can be tied directly to the fact that the working and middle class have had no real raises in income since 1980, and have seen their savings and equity eroded by inflation and recessions.