Nobody knows whats wrong with my car PLEASE HELP!!?

[Y0GtB3AR]

i drive a 1994 Mercury cougar XR7 with a 4.6L V8 when i start it white smoke comes out of the exhaust, when i drive it and began to let off the gas it will shut off, it has a little shaking to it, the only things i have done to it were 3 in. piping exhuast back from the headers, took the cats and resonator off but have mufflers, k&n air filter that's it and nobody knows what's wrong with it. It has just been sitting for 5 months and now i have a good 900 dollars to fix it but i just want to pay for the repair not for them to find out what's wrong with it then fix it. SO IF ANYBODY WHO KNOW WHAT THEIR TALKING ABOUT I WILL LISTEN THANKS!!!!

 

[yes_its_me]

Start with a hands on mechanical diagnosis.
Compression check, radiator pressure check, leak down test, etc.
Make sure that you have an engine that is worth while to repair.
I doubt if your problems are caused by the removal of the cats.
Sadly, a competent tech should look at it and that will probably cost a few bucks.

 

[mybuttstinks2008]

The smoke is oil blow by in the cylinders or a small tear in the head gasket letting moisture seep into the cylinders. It sounds like your throttle position sensor is bad. Possibly the MAP sensor too. More info would help. Miles and does the shaking occur when you let off or around 45-55mph...Generally a shop does not charge for diagnostics unless you do not have them do the work.