i have been trying to figure this problem out for a while now but i cant figure it out, when i try to get on the freeway my engine starts to miss fire but if i get off the throttle for a few seconds then get back on it it levels out then starts to run correctly i have changed the spark plugs ignition wires and distributor i have also put in a new fuel pump, i do have a small exhaust leak but i can never find it, it sounds like its coming from the passenger side if any one has a similar problem i would be grate to hear what you have to say

 

When it misfires does it fell like it's cutting out and jerking hard or is it more subtle? Only reason I ask is I had a similar thing happen on my 2000 Blazer until I looked down and saw the tach jumping at the same time - trans was slipping just a little. It took me a while to figure it out because it felt like a slight hesitation. Just a thought.