89 225 excel RPM drop then up

[Operaman]

Hi guys. 89 225 excel the while under way say at 4400 will drop to 4200 then after a while goes back up. It also will do it at 4000 to 3900 but much less often.
I am thinking TPS? Any ideas? Thanks

[slim]

sounds to me that your headed in the right direction. check it with a analog meter to make sure.

[Operaman]

Slim, is there a voltage range to look for? And I would think it is to be even increase and decrease with the throttle up and down. Thanks

[slim]

you want to move the throttle very slow and look for needle jumps of any kind. set the meter to 2vdc to start, then once you get to about 3/4 throttle position, you will need to set it to 10vdc. i wish they meter with a 5vdc scale, i have looked.

[Operaman]

$300 part, I will be testing voltage. I think it is what is going on, but should be sure.