I have a 1987 Defender 90 with a 2.5 TD engine. Occasionally the engine wants to runaway which causes me to drop the clutch to bring it back. It happens when starting out in 1st gear. I had a very dirty metal mesh filter screen on the pickup tube made the truck act as if it were running out of fuel when going 60-65 miles per hour. I'm getting in the process of sorting that out and was wondering if that could have anything to do with the engine "running away"....perhaps it was sucking air? Thoughts?