Here's the problem. Just got a new timing belt installed, it shedded the old one. Left the mechanic and a few miles later it started to hestitate at low speed, turned around and went back. It quit hesitating but I went back anyway, he suggested I get it filled up which I did. The next day, I drove 10 miles or so before it started happening again. It continued to cut out worse and worse, this is at low speeds. I towed home and looked in the archives, everything pointed to the in-tank pre pump. I was so confident I replaced it. No change, still a stumble goosing it at idle. It idles perfectly.

My understanding is that if the main fuel pump had failed , it wouldn't run at all. What now?

Thanks in advance, Ar