Car trembles / shakes at low and medium speeds?

[MsPhenomenal]

2000 ford mustang

I just had my brakes done (new routers) 3 months ago, bought new tires 1.5 months ago had a tune up (sparks and wires) and another transmission put in two weeks ago.  2 days after I brought the car home ( after transmission install) my car start shaking when I pull off from a stop sign or light, while driving at low speeds and while driving at medium speeds.  I sometimes notice a faint overheating smell after I stop. The "check engine" light has been on for awhile.  The mechanic said the shaking/ trembling should have stopped after he changed the wires, because the diagnostic reads as a back fire.  



I've already spent $3000 (the dam* car isn't even worth that much).  Any ideas what the problem may be because the mechanic doesn't seem too sure.  PLEASE HELP!

[WillS]

Yeah, your "mechanic" is the problem, get your car out of that shade tree shop asap and take it to a reputable repair facility that employs ase master certified technicians. They should be able to diagnose the problem for an hours labor. There is no code out there on any car specifically for a backfire.

[Gerald]

Take the car back to the mechanic...

[BIGK]

it could be that an engine mount is loose or broken. that can cause kinked wires and bad air flow

[guillermo31sbcglobalnet]

Does it do it when it's at low RPM's?  I had trouble recently with my Blazer.  It would shake and rough idle when at low RPM's, and it turned out being the EGR.  I also had a check engine light saying cylinder misfire.

[armona4708]

Sounds like a fuel pump problem. That would explain the backfire. If your motor back fires and pops you are running to lean and on a fuel injected car one of the main causes of this is a weak fuel pump. But not the only cause.