loss of power

2005 LS 2WD It has no power when i first turn it on. If I sit and let it idle a couple minutes the problem goes away, but if i get the rpm up to around 4000 then it looses all power till I stop and shut the car off for a minute. I went to autozone when it first started and it showed codes for...

today my 99 tahoe,old body style,developed a problem i believe to be a bad ground somewhere.its been raining alot here , i live on a gravel road full of potholes which i believe caused the problem.every hole or bump i hit the headlights flicker/turn off,the left turn signal indicator lights...