I have a surging either form the engine or transmission. 1990 v-8 89,000 miles. When I am in 4th and just touching the accelerator lightly the car jumps (surges) you can depress the accelerator more and it stops or let off of it completely and it stops. I had the Trans. serviced in the last 3000 miles( Fluid & Filter) Mobil 1 syenthic ATF. Some times it also is slugish in shifting from 2ed to 3ed. Thanks