I have a 91 3vze auto 4runner that initially had a cold start issue. Found a deal cold start valve and sensor on ebay so I said what the heck and got both. Im waiting on the sensor still but today while accelerating the rpms would just drop down 1500 rpms or so at random times. Idle was totally fine, strong and normal. So I thought maybe the tps was to blame, maybe its a fuel pressure issue, maybe they are unrelated, maybe they aren't! Im new to toyotas so any help is appreciated guys! Thanks in advance.

 

Ideas: A poorly flowing fuel filter, a bad injector that cannot keep up with the demand, a vacuum leak in vacuum hose or the intake.

 

Im at work on a 48 hr shift so I can't really tear into things yet but don't you think the filter and injectors would both affect the idle at least a little? I've yet to check for vacuum leaks though

 

a dirty filter will allow enough fuel at idle because it doesn't need much, but at a higher rpm it can't suck enough fuel through the dirty filter. Chances are it should to be changed anyways.