Chosen Solution
After driving 15-20 minutes the RPM gauge jumps from 1 1/2 to 2 RPM and the motor rev’s up like I’m pushing down on the gas pedal but I’m not. My foot is steady on the pedal. I think my engine fan is turning on when the RPM gauge surges and turning off when it stops. Why is it doing this and how do I fix it? How do I know if it is the engine fan or not? Update (09/25/2018) Hi Travis, no I’m not running a/c or heater when it happens. It happens after the only after the engine warms up. It doesn’t happen every time its warmed up either. There are times the RPM gauge will surge for 10-15 seconds then stop, and do the same thing a few minutes later. But that don’t happen every time either when it surges back to back. It seems to happen more often during summer months.
I would start hunting for a vacuum leak. Look for any disconnected or dry-rotted hoses or a cracked air intake and listen for a hissing/rushing sound from your engine. Cleaning your idle air control valve may also fix the problem. I’d also check your coolant and make sure it’s not low. I assume there isn’t a check engine light, but if there is take it to a parts store and have them read the codes for you. A failed engine coolant temperature sensor could also cause surges.
