The aerostar is the 3.0L version, automatic, with 105k miles. Recently it has begun jerking while driving, as if the thrust is cut out for a split second. It occurs both when accelerating and when at a constant speed (norm 45+ mph). I recently had the transmission flushed and filter replaced and had some Lucas Oil transmission fluid added to the system. Friends have recommended that I get the fluid replaced again. They say that not all the gunk gets cleaned out during the first flush. The fluid was dark and filter clogged according to repair guy prior to recent flush. I drove it x-country (TX-NV) after the flush with 1k lbs of stuff in the car. It was fine during x-country drive, but is acting up now. Any ideas? Do I really need the trans flushed again or a new trans or something else?

Alright, I got a 94 Suburban 4wd with 5.7L engine and auto tranny. Recently it started shaking while having the throttle pushed in. Today we changed the plugs and wires and the shake became more noticable so I started paying attention to my gauges. It doesnt matter what speed I'm going as long as the throttle is pressed in and the rpm's are below 2500, it shakes. Once the rpm's reach 2500+ or the throttle is let up on, it stops shaking. What are my most likely causes?