1998 eldorado is stumbling
 

Hi guys. I have a 1998 eldorado. Car set up for about four years before I got it. Car would crank and run but it was hard to start. I replaced the fuel pump and filter and it starts like a dream now. However, when at highway speed and you slow down to turn off the road, when you get back on the gas, there is no throttle response. After you press the peddle about three times, throttle response returns. The car doesn't go dead, it's just like there's no gas there. Also this does not happen all the time, just intermittently. What could my problem be? Thanks in advance for any help.

New problem as of today. Now when sitting at the stop sign with foot on the brake the car begins to lunge as if you are pressing the gas. Now what?

Thanks for all the help.

are there any codes?