This happened twice lately: once after leaving Xterra ('03 SE 2WD) parked tilted with driver side up on 2 ramps & again weeks later after leaving it parked overnight with front end up on 2 ramps... Fuel gauge suddenly reads E, though tank is more than 1/2 full. Starts up & drives fine under 30 mph 3/4 mile to main road, then chugs & bucks like it's running out of fuel when i try to get it up around 40 mph. After a restart or two the gauge responds accurately and it runs normally. After the 1st incident i replaced the fuel filter and have had no issues till parking it with the front end up last night. I can understand why parking at an angle/incline might affect the fuel level float/arm and send a bad read to the gauge, but why would it also act like it's low on fuel when it's not?