I have a 2001 SX with low hours. Last couple of years I only used it for a week in Tahoe. Had it serviced last year then put in storage. This year at Tahoe, it ran fine at low rpm, but ran really rough at 9mph and wouldn't go faster than 10. Been in the shop since, getting a new fuel pump [high pressure and low] and a new fuel pressure regulator. Still not fixed. Any ideas, because they're out. Thanks