Need help with 1999 Toyota 4 runner

i bought this truck like a couple months ago and it ran really good for about a month. Sometimes, while I'm driving,(foot on gas) it seems to not get any gas and I watch the rpms go down like it's not getting any gas. Then the engine light came on and I took it to the shop and they said it was the mass airflow sensor, so we cleaned it. Then it started doing it again. So I myself replaced the sensor. Still does it. Then the battery light came on, they said I needed a new alternator so we replaced that. It drove fine for a day and it started doing it again! The mechanic drove it with me in it and it did something new, it stalled when we stopped. He started it up and it drove fine. So it's been at the shop for a week and no one can figure it out. Does anyone know what might be the problem? Please help!!!

 

Have you checked the fuel filter? Should be an easy and cheap fix.
Symptoms

stalling when idiling or rough idle

Feeling bogged down when driving or accelerating.

Hard starts

 

Ok thanks I will try that

 

If it's the 3.4 V6 replace the throttle position sensor. Had a similar issue with my Tacoma until the part completely failed and went into limp mode.

 

I was going to suggest that too. I replaced mine about a year ago for some rpm issues I was having. I have a friend who is selling them. I just asked if he had anymore. Here is what he says about them.

$28 Shipped....Brand new in box NEW Genuine Toyota Throttle Position Sensor 89452-35020 for most 1996 to 2000 .... 3.4 V6 and 2.7 L4 4Runners.
This is the 3 Prong TPS and some vehicles take the 4 Prong so be sure you check your part number and it matches this one exactly or it won't work for you.



Works for many other Toyota cars and trucks. I am located in Ocala Florida.


Part lists for $62.23 but you can get online for around $45.00 ....Will sell at $28 shipped
I have a few of these here so if you want to pick up more then 1 let me know. Paypal accepted

Symptoms of a Defective TPS

The function of the throttle position sensor is to supply information to the car's computer about the position of the car's throttle. It contains electro-mechanical parts, which are prone to weathering. A malfunctioning TPS can result in improper or no data being fed to the car's computer, which monitors engine performance, in respect to the fuel efficiency of the car.

A TPS usually detects heat, light, and even moisture. It takes all the necessary measurements and sends it over to the Electronic Control Module. The biggest problem with a TPS is that it's so small and intricate, that repairing it is almost always out of the question. But the good news is, a decent TPS isn't that hard on your wallet.

One unique thing about TPS failure is that all the symptoms may show up at the same time. It doesn't mean that they show individually, but it often happens that you'll notice more than just one sign.

The 'Check Engine' Light is On
This is the first thing that you'll notice. The light is meant to tell you, the driver, that something is wrong with either a component of the car, or its sensor. It's always advisable to get your car checked out by a mechanic as early as possible if this light is on.

Bucking and Jerking/Hesitation while Accelerating
Another common symptom related to a bad TPS is the jerking of the car, especially when accelerating. Without proper inputs from the TPS, the on-board computer is unable to guide the engine to work at optimum levels. (this is why I wanted to replace mine in the first place...It would happen at around 55 MPH and the truck would kinda stutter or jerk while I was accelerating to get up to speed)

Idle Surging
This problem usually comes in conjunction with the above one. Similar to getting jerks while accelerating, with a faulty TPS, the computer cannot tell if the throttle is fully shut when the car is idling.

Sudden Stalling of the Engine
This can happen anytime, without any kind of warning, while driving or idling. The TPS can give a bad input, prompting the engine to stall.

Sudden Surge in Speed While Driving on the Highway
This is a particularly hazardous situation. What usually happens is that at high speeds, the butterfly valve inside the throttle may close up, and if the driver pushes on the pedal harder, the valve 'pops' open suddenly, giving the car an unintentional burst of speed. All of this happens if the sensor is unable to detect the closed position of the throttle.​

 

He still has some available. Let me know if you need one and I'll give you his contact info.

 

Tucson, Does he have both the three prong and the four prong?

 

Solely 3 prong available.

 

I believe I have the 4 prong. Those are impossible to find..I would like one to keep around as a spare.

 

You check the usual dealerships? Camelback and Toyota of Dallas? I'm sure I could find a used one but that would'nt really bring any security as a spare.

 

Thanks for all that! Makes sense. I will try that next!

 

Thanks guys for all your help! I bought the tps sensor and it worked! She's running like a champ now!

 

Great! Glad we could get her healthy again.