Hesitates At 1000Rpm Intermittently

[mrmdubb]

Hi, I have a '99 RX300. Every once in a while it hesitates between 1000rpm and 1400rpm. After that point it drives fine again. This never happens after I just started the engine cold. However, after I drive the car for 5-10 minutes the problem appears. It's especially frustrating because the hesitation won't happen every time. I'd say it happens 50% of the time after the car has been warm and driving for 5-10 minutes. I just accelerate out of the red light and I feel a couple hesitation/jerks in the engine until it passes 1400rpm. The rpm isn't skipping and catching so it doesn't feel like the tranny.

I recently changed the plugs, timing belt and do regular maintenance. My mechanic thought it was the throttle body so we replaced that yet it did nothing.. .huge waste of money. Anyhow, now the mechanic wants to actually open up the fuel injection/throttle system to clean it out manually instead of just adding an additive to try and clean it out. I've had the usual RX issues (IAC valve, MAF, o2) and this is definitely different from those so I'm out of answers.

Any experience with this? Thoughts? Suggestions?

[carguy07]

Hi, I have a '99 RX300. Every once in a while it hesitates between 1000rpm and 1400rpm. After that point it drives fine again. This never happens after I just started the engine cold. However, after I drive the car for 5-10 minutes the problem appears. It's especially frustrating because the hesitation won't happen every time. I'd say it happens 50% of the time after the car has been warm and driving for 5-10 minutes. I just accelerate out of the red light and I feel a couple hesitation/jerks in the engine until it passes 1400rpm. The rpm isn't skipping and catching so it doesn't feel like the tranny.

I recently changed the plugs, timing belt and do regular maintenance. My mechanic thought it was the throttle body so we replaced that yet it did nothing.. .huge waste of money. Anyhow, now the mechanic wants to actually open up the fuel injection/throttle system to clean it out manually instead of just adding an additive to try and clean it out. I've had the usual RX issues (IAC valve, MAF, o2) and this is definitely different from those so I'm out of answers.

Any experience with this? Thoughts? Suggestions?

1st find a new mechanic! Check engine light on? What did you use for plugs?