2005 GMC Jimmy

I am not sure what the problem is and am guessing it is either mechanical or electrical. This is what is happening and it doesn't happen every use but about 1 in 3-4 uses so fairly often now. When I start the vehicle the gas gage doesn't move up and this tells me I will have problems. When I put the vehicle into drive or reverse all the dashboard warning lights flash on and off, the rpm, gas gage go up and down and when I put my foot on the gas pedal I almost have to push to the floor to get going. Once moving if I shift from reverse to gas and put my foot on gas you can sometimes hear a loud "cracking" noise. Sometime the lights on the dash board take upto a mile of driving to start up so I have no idea how fast I am going and you can't see the indicator to say if you are in drive ect.