Slight repeated increase in RPM

[PT-4]

Cruise set at 55 mph on highway, say my RPMs are at 1400. About every 5 seconds, at a regular interval, there is a slight increase in my RPM, to say about 1450. Anyone else have this issue and know the cause?

 

[Wild one]

Cruise set at 55 mph on highway, say my RPMs are at 1400. About every 5 seconds, at a regular interval, there is a slight increase in my RPM, to say about 1450. Anyone else have this issue and know the cause?

Start with the easy /cheap stuff.Clean your throttle body (if you remove it to clean it,disconnect the negative battery post first) pull the pcv out,check to make sure it looks clean and still rattles when you shake it,check your intake manifold bolts (we already told you how,even if you haven't found a video),throw a bottle of injector cleaner in the tank ,try a differant gas station for fuel.Although a 50 rpm rise isn't much,and could even relate to the tach signal,as the tac's aren't all that accurate,but try the cheap/simple fixes and go from there.