Engine Performance problem
1991 Lexus LS 400 V8 All Wheel Drive Automatic 135000 miles
hello all, I have a 91 Lexus Ls 400 135000 miles, nice car and drives good in the winter time and at night time when the temperature is cool. But when it gets a hot like in the summer and I drive it for about an hour on the road or even when I run it for about an hour, it starts to loose power and jerk like its gasping for air.
When I put it in park to idle, it revvs itself between 0 and 2000rpm. If I turn off the engine and let the car sit until the weather cools off, it starts to drive well again. A few mechanics could not determine what is wrong. Lexus dealers are having a problem determining what it is. I need a possible explanation so I can pass it on to the mechanics. Thank you all.