When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My '99 RX300 w 89k miles will start chugging if I get on the freeway and consitently go at the same speed for a period of time. For example, if I go 55 mph for 3-5 minutes. Once the chugging starts, it will stop if I give it slightly more or less gas. Also it does NOT do this on surface streets as I'm continually varying speed and throttle.
Does this sound like an A/F ratio issue?..maybe A/F sensor? The CEL is lit.
If the CEL is lit, please have it read by OBDII (folks typically get it dumped by going to AutoZone). Remember do not reset the CEL by disconnecting the battery as it will wipe out (some/most/all) codes.