My 2004 WRX has a 4EAT transmission. The transmission shifts with no problem when driving it easy. It slips when shifting to 3rd if accelerating anyway more aggressive than easy on the pedal. When it does slip all I have to do is let it rev down (revs high when slips) and coast shortly before it hooks up. It also slipped when in I got into stop and go traffic on the freeway and lost 3rd/4th. This time it just drop out when easing along and stayed gone. I was able to get to the next exit in the stop/go traffic with no problem since traffic never got above 40mph. I as in the city with the speed limit at 35 so I was able to get to my destination in 2nd gear. The car was parked for 5 hours so it cooled down. I was now able to drive the 60 miles home on city streets and freeway with no problem. This time I was not in the stop and go traffic and the transmission drove/shifted through all the gears smoothly the entire time. Note that I did not get aggressive on the throttle at anytime. I suspect the solenoid that controls 3rd/4th is faulty or do I need to get a remanufactured 4EAT?