I have a 92 chevy 1500 4x4 with a 5.7 with 230K miles. I just bought the truck and the guages occasionally seem to work but most of the time they jump all over the place. Also, when I turn on the turn signals they are all effected including the engine performance. Sometimes the engine sounds great but then revs up and then acts like it's about to die.

Once today the air came on by itself at start up and was erratic like the rest of the guages. I have not had the AC or heat on the last few days so I was supprised that it came on and seemed to be acting up just like the guages and the engine idle. At times they all seem to be acting up in harmony, if that makes sense.

The idle is very low most of the time but sometimes seems alright. When reving the engine it sounds good and smooth with no unusual noises but when put in gear the idle becomes irregular and the acceleration is erratic.

The only thing I have done to date is change the very old plugs and wires without any difference. I also added sea foam to the gas tank.

For the most part, the truck is very dependable as it starts right up and it accelerates fine though not strong.

Probably a separate issue but the door locks act like they want to work but seldom do. Power windows work okay though they seem a bit slow.

Thanks in advance for any help.