My gmc envoy 2002 also drops at night , but when we turn it on, it comes back up. i was wondering if lisa that had the the same problem fix the problem by changing the shocks or was it some thing els

Here's a link Lisa to your firing order. Specifications Firing Order Cylinder Location AutoZone com

sounds to be a bad head light relay it can be over heating

Check and make sure nothing is staying on ie. lights. Check the cells on your battery to make sure they are good. It is possible the battery isn't holding a charge.

It may be a transmision linkage problem. Try shiftind gears from park, N, D, 3, 2 ,1, back to park.

mine was doing the same thing i found a vacum leek fixed it now it wirks fine

turn key to on, do not start, pump gas pedal to the floor 3xs. within 5 seconds, then wait for it to go out..

Try a new oil pressure switch first,if that does'nt repair the problem then get the oil pressure tested.If it tests low then the problem is internal and the motor meeds to be dissasembled.

sound slike you may have unplugged or disconnected somethine else or the spark plug you put in is bad or inpropper gap

use a blow tourch and carve a hole next to the doors

If your 2002 gmc envoy or sierra will not even turn over with a kown good battery try starting it in nuetral then go back to park and try starting again. There is a park nuetral safety switch that can malfunction. Turn the key on then shift into nuetral, then turn fully to start.