A number of months ago I posted about a 1989 240 wagon with a lot of miles that began to have some rough idling problems, along with the check engine light coming on (it indicated fuel system error, although the OBD wouldn't display the error code). Here's the original post with the advice folks gave me then.

http://www.brickboard.com/RWD/volvo/1402265/220/240/260/280/240_rough_idle_intermittent_fuel_system_problems_obd_led_stays.html


To recap, sometimes, upon starting, the car would idle roughly for a minute or so before it suddenly became smoother (perhaps the ECU sensing and adjusting?). I changed air and fuel filters, checked fuel pump relay, checked ECU, tested with another Air Mass Meter, changed plugs, cap and rotor, wires, all to no avail.

Then I took the car on a drive down to San Fran from Seattle, and for the duration of the trip it ran and started great, and continued to run great for some weeks afterwards, before the same symptoms started again. Now I've taken another trip across the country to Maine, and the same thing happened. It ran and started perfectly every time during the duration of the 3000 mile trip, and for a few weeks afterward, but now symptoms starting up again. Anyone have any ideas?