1998 GMC Safari engine knocks

I had a new flywheel and starter put on my van and everything was fine for about two weeks then the engine started ticking the it got louder and louder, after its warmed up there is a positive ticking or knock that gets real load but when I am sitting at a light you can hardly hear it. And when you give it gas to start going after a light, and let off suddenly the tick kinda floats in a final rapping. Till I give it gas again. I did call the mechanic that replaced the flywheel, he came over listened to it then said he had to do some checking and then now its been over 3 month and haven't heard anything, and now when I call all I get is noisy cell phone chatter in the back ground. Would it be easier to repair the motor or buy a low milage used one and have it installed?