91 AllTrac (awd) Previa, auto trans, 190k, has just had a new head put on, gaskets etc, plugs, wires. It runs fine down the road, but in gear at idle, it misses. The mechanic has had it back and can not find it. He readjusted timing, alternately pulled plug wires, etc. For the moment he/we have given up. Any ideas?
Compression test on each cylinder might be helpful in finding the cause.