rebuilt engine installed, have a few questions / issues

[fox-gt]

I just got my car back from having the engine rebuilt. I upgrade allot of the parts (aluminum heads, cam, intake, 70mm tb, new torque converter, tranny cooler). The engine runs great but I have a few questions.

Breaks.
I'm not sure if it was the car I drove for the last two months or if I'm not used to them but the breaks are not good at all. If I take off and have to stop right away, the car doesn't feel like it wants to stop. I have also rolled through a few stops signs and almost hit someone.

Sometimes dies on startup.
If I start it up, throw it in reverse or drive right away it will die. If I wait about 15 to 20 seconds and take off, it is fine. Never dies after it has been running for a while. It did this a little with the stock setup but never actually died, just felt like it was going to.

Downshifting.
If I cruise up to about 50 mph to 70 mph and let off the gas, when I hit about 40 mph (under 1000 rpms) the car starts jerking really bad. If I press the break, it will down shift and is fine. Never had this problem with the stock setup. Never does it on acceleration, only on deceleration.

It is frustering when you pay allot of money to have it fixed and it comes back with new problems.

 

[bill302]

sounds like you have a vacuum leak...a vacuum leak will cause all the symptoms listed above. take it back to the rebuilder/installer they need to find the vacuum leak they might have not reconnected all the vac. lines this is a common occurance in a rebuild...sometimes its hard to find all those hiding vacuum connectors and/or lines break..ect...listen real close under the hood while car is idleing and see if you hear an unusual hissing sound and ensure your break booster vacuum is connected properly.