2010 Rav4 252k 2.5 engine I'd had it since April a one owner it has regular synthetic oil changes every 5k miles I've replace maf plug coils intake manifold iac assembly both 02 sensors i've been chasing this rough idle since purchased no check engine light. when in drive stopped at a light the whole engine shakes including tailpipe hood and inside the vehicle badly once the rpms drops between 650- 600 the weird thing is it runs awesome before considering getting rid of it what are my next options?
Instead of throwing parts at it, get it scanned to find out what the problem really is. Might be something as simple as a vacuum leak.
Toyota scanned it. erratic iac reading suggested replacing intake manifold iac assembly due to mileage. had it done.