Anyone ever had a 1996 Jimmy that rocks when you have a long uphill climb. I'm up about 3,000' in some mountains and go down and run around in the city at sea level without a hitch. But when I start climbing a steady 3-5 degree grade, I have to keep the rpms above 2000 or the Jimmy starts rocking, especially if I drop below 1500 rpms. It's a pain because if there's traffic going up the hill with me I really start rocking and I really think the car will die on me, and this is something you just don't want to do going up this narrow uphill mountain road. It's not electrical; that's been done. In fact, nothing up front seems to be causing it. A Master Mechanic did all he could there plus a lot of road tests where we created a lot of demand on the engine and nothing stopped the rocking. The Master Mechanic had to leave the area and his final suggestion to me before he went back to FL was "it could be the fuel pump but there are no strong indications that that's what it is and I don't want to just start shooting from the hip replacing parts cause that could become very expensive." Anybody had this and solved it? I'd appreciate details from anyone who solved it or really knows how.