While Cheltenham scored their first goal of Johnson's reign at Adams Park, it mattered little as Gareth Ainsworth's men got their League Two automatic promotion bid back on track in a 2-1 win.
Aaron Pierre and Alfie Mawson got the goals for the hosts, who picked up their first win in three, leaving rock-bottom Cheltenham three points off safety despite Durrell Berry's equaliser.
Fellow strugglers Tranmere also saw their fading survival hopes dimmed further as Barry Corr's first-half winner gave Southend United a 1-0 victory at Roots Hall.
Hartlepool United remain a point clear of the bottom two following their 1-0 defeat to 10-man York City at Bootham Crescent.
Dave Winfield's dismissal failed to throw York off course as Luke Summerfield's deflected shot after the hour took them a step closer to guaranteed safety.
Carlisle United's 1-0 win against Dagenham and Redbridge - a game that saw both sides reduced to 10 men - helped drag Mansfield Town further into the mire.
Adam Murray's men fell to a fifth consecutive league loss as they were beaten 2-1 at Plymouth Argyle in a result that sees them drop to 21st.
Mansfield sit six points above the drop zone going into the final four games of the season.
At the top, the leading trio all picked up maximum points with Shrewsbury Town hammering Exeter City 4-0 thanks partly to a Jean-Louis Akpa Akpro brace.
Matthew Palmer scored the only goal for Burton Albion at Luton Town to keep them a point clear at the top, while Stevenage moved into the play-off pack with a 2-1 success against Northampton Town.
Newport County are the side to drop out of the top seven as Ryan Lowe and Daniel Nardiello sealed Bury a 2-0 victory at Rodney Parade.
Alex Kenyon's double gave Morecambe a 3-1 win over Portsmouth and AFC Wimbledon and Oxford United played out a goalless draw.
