when you rev the car up, it drops maybe 10-20 rpms and then revs up. i don't like hesitation, is this supposed to do this or is there a bad sensor. i do have a cel but it is a temp switch being unlpugged.(i need a new fan controller, the fan comes on for about 10 sec. and then goes off, it is a new sensor, so i unplugged it and the fan stays on.) any ideas