Okay, here's my trouble...I bought an old 1988 420 sel as a restoration project and spent over a year patching up and polishing the job. After a new suspension, new rims and tires, transmission repair, paint job, tune-up, and custom parts installation, I thought I was doing pretty good. In fact, the car looked sharp and I was well-pleased with the results. However, last year I drove to Myrtle Beach (from central Kentucky) and back. Two days after my return the timing chain broke and ruined the engine (worst scenario you can imagine: broken pistons, bent valves, etc.) Needless to say, I had to replace the engine, and so I did, with one that had only 75,000 miles on it. By the way, its not diesel. Ever since this installation, the car has been running like someone poured mud in the tank and my mechanic has tried everything he knows to do. The engine seems to be in fine working order, but something just isn't right. My idle is very rough, the car is difficult to start, (it usually cranks and dies or else takes several tries with me stomping the gas). I also have very poor power. The transmission shifts hard, but that may be another matter, because it shifted a little rough before. Now, though, it kicks. I've put far too much money into this shiny beast to just abandon it. But driving is no longer a pleasure. I'm not that great at auto repair-changing the oil or a tire is about as far as my skill level goes, so if anyone has advice then simplicity is bliss (although I may need technical names for my mechanic). I may need to take the car somewhere else, but he's worked very hard for me and sincerely tried to fix the problem (after the problem remained, he didn't charge for his last attempt). I do need help though. If anyone has any ideas or has experienced similar problems before, please share pronto! Thanks a million!