Ok so I installed a header and a intake manifold on my friends 420a. Now im a 4g63 guy so its pretty much the same thing so i know its on right. I made sure all the sensors were pluged in right but there still is a problem. When i put the battary back in the car it was dead so i charged it and took the car for a spin. Was driving just fine untill i got on it and the car kind of sputterd out and the electronics went crazy. Car started to drive slow like i was driving on 3 cyl. Kept driving the get the car home and it fixed it self. So now a few days later I tried to jump the car again becuase it will no longer keep a charge. The car wouldnt charge at all, the negitave cable started to smoke and it looks like the alternater choke fuse is blown. Please let me know any ideas on what this could be. Also if you have done a swap before which sensors need to be pluged back in? There are 3 if im not mistaking.

Thanks ahead of time
Jim

well first and foremost replace the alternator fuse, because you need the alternator running in order to charge the battery while driving. When the alternator is not working the car relies on the battery alone for all its electronic needs and it will drain it quickly without the alternator recharging it. Depending on the manifold and the location of the MAP sensor the ECU might have needed to adjust, and incorrect MAP readings or an intake manifold leak would result in a rich condition and poor driveability.

Check the chassis, block, and manifold grounds? Sounds like the alternator is bad, and/or you might have forgot to reconnect the ground from the firewall to the intake manifold.