I just got the full tune up done...plugs,wires,cap,fuel filter,oil filter,oil,air filter and yet I still have an issue that I think I have noticed coming on for about five or six months. I am including all that I can to help with diagnosis.

Let's start about a year and a half ago when I was driving from south san diego to north san diego... my a/c comp. clutch seized which caused the serp. belt to shear and then the truck over heated to the point where steam was coming out from under the hood, etc. I was in a bad part of town and didn't want to stop and that's why I took it that far.

Now forward to about a year ago... the water pump went so I replaced the pump and thermo. Then soon after the starter went so I replaced as well.

Now about six months ago while getting a jump from a mech./tow truck guy he said it was running rough which i agreed and we thought it might be the arching wires. So that prompted the tune up some several months later. Now once the tune up was complete it made the situation more prevalent that I might be dealing with something more then bad wires.I took it to mechanic and they tested the compression in which they said it was low in four and six cylinder. This would explain the knocking as some of the cylinders probably four and six were not firing. There was a knocking/clicking from around 1400-1700 RPM and it doesn't always happen it is intermittent. But sometimes it is fairly prevalent. I had a dealership check it out and they didn't even hear the knocking till I took it out and showed them. they thought it was an exhaust leak and they fixed that for me. then i asked that they check by taking off the vavle cover and seeing if it was a burnt valve or stuck valve. they said they figured it was something more then that and recommended a new engine. well this is my second engine and it only has 95k on it... so no go there.

Now having not done or not able to do a wet/dry compression test myself, and not being able to test dip stick,radiator,exhaust,carb. for non sealing valves...I have this question. Wouldn't it make sense that with the overheating, and now two cylinders with low compression that is intermittent. Would it make sense to guess that I have a head gasket that is getting ready to go completely? When I had the oil changed there was no mention of bad coloration of oil. I don't have any smoke issues out the tail pipe. She isn't running through excessive oil, and there is no backfiring.

Any and all answers would be greatly appreciated.

I am trying to sell the truck, if the fix is too expensive, which has many added bonus such as many new parts including trans. and rear end. what do you think a fair price would be seeing as how it still runs fine and has many new parts...?