This style, interwoven with melodic hammer-ons,[3] gave Johnston an early signature sound in popular 1970s rock music.

His greatest musical influences during his youth included Little Richard, Bo Diddley, Elvis Presley, James Brown, and other rhythm and blues artists featured on the radio in the 1950s.

[6] Johnston moved to San Jose to finish college and started playing in bands around town.

[7][8] It was there that he met Skip Spence, a former drummer with Jefferson Airplane, and guitarist/founding member of a group that had a major influence on the Doobie Brothers – Moby Grape.

"It didn't matter if they played B-3 or drums, guitar, bass, or horns, they all ended up in our basement," Johnston recalls.

Johnston and Hartman soon formed their own band, Pud, featuring Greg Murphy on bass.

Pud played many clubs in and around San Jose, including the Golden Horn Lounge (which no longer exists) in Cupertino, California.

Hartman and Johnston lived in the 12th Street house for about four years; whereupon Dave Shogren joined them to replace Greg Murphy and Pat Simmons was recruited, they had the nucleus of a new band, and Pud gave way to the Doobie Brothers.

[9] In December 1973, the British music magazine NME reported the relatively trivial news that Johnston had been arrested in California on a charge of marijuana possession.

Restored to fitness in 1976 and briefly back in the band, Johnston contributed one original song to Takin' It to the Streets ("Turn It Loose"), and also added a vocal cameo to Pat Simmons' tune "Wheels of Fortune".

None of Johnston's songs appeared on Livin' on the Fault Line, though he had written and the band had recorded five of his compositions for the album.

After a few years of restored health but growing differences in musical direction between band members, Johnston finally left the band in 1977 to pursue a solo career that produced two albums with Warner Bros: Everything You've Heard Is True and Still Feels Good (reissued on compact disc by Wounded Bird Records), and Billboard Hot 100 hit "Savannah Nights" (#34 Top 100 Billboard Hit −1980).

In 1985, Johnston toured US clubs with a group called Border Patrol, that also included former Doobies Michael Hossack and briefly Patrick Simmons.

This event led to the permanent reformation of the band, with Johnston again performing alongside co-founder Simmons.

At home I have a Stratocaster and I have some older guitars I have had for a long time, an old Les Paul, an old 335, a couple Strats and a Telecaster.

"[11][14] While primarily an electric guitarist, Johnston also plays acoustic guitars for exploration and song writing.