Sunbed shaun

Over the last few weeks I noticed my fiesta was making a quiet popping noise in the airbox and at the same time the idle goes up and down slightly, it only happens when the engine is warmed up. I was told it is most likely the MAF sensor so I changed it and its still doing it, then today I noticed the throttle is sticking a little bit at times, say if I was in 3rd doing 3000rpm then slow down to 2000rpm, drop into 2nd gear the revs go up as normal then stay higher as I'm slowing down while the clutch is in. Any ideas on what this could be? Could the idling problem be what's causing the quiet popping?

Sunbed shaun

Think the popping problem might have stopped since sorting the wire going to the powersteering sensor. Cut the old corroded wire off, rewired and connected it. Took it for a drive to warm it up then I parked up leaving it ticking over to listen, idling is perfect again, not sticking and not a single pop in the airbox