Ok ive got a 99 1500 with a 5.2. Its really sluggish running now. And if im running the a/c and mash on it then it seems to suck vaccume out of the flaps that close vents and therefor i loose my a/c. And at the same time it seriously looses power for a few then picks back up... It has no off the line throttle bite and cllimbing hills is a joke. Wants to kick down a gear and run like 4 to 5000 rpm to get up the hill... Anybody got any suggestions on why it sounds like im loosing vaccum? And it sounds like theres fluid running all over the place when i mash on the throttle then as it picks up the sound go's away.

 

the fluid you hear is the heater core. You might have a leak. Try burping the system. As far as the other stuff goes, read these.

https://dodgeforum.com/forum/2nd-gen...um-thread.html

https://dodgeforum.com/forum/2nd-gen...ild-vents.html

 

Plenum leak lol

 

I would check the upper intake gaskets. When they tear the engine will have vaccum in the crankcase, thus loosing vaccum in the upper intake where the feeds come off for your HVAC unit. Remove the PCV and air breathers. Plug the air breather hole with your hand. With you other hand feel for vacumm in the hole where the pvc was taken out of. If there is vacumm there the upper intake gaskets have more than likely failed. If it's fine put a vaccum gage on it and see whats going on. Does it loose power only with the A/C on?

 

Sorry, but it's not the "upper intake gaskets" . As a matter of fact, there is a Dodge TSB Vacuum test, and it's a waste of time. Unless the lower (plenum gasket) is severely blown out. Plus, if the cat is clogged or on it's way, the vacuum test will be false anyway.

 

More so when its cold... And also u can here the trottle body whistel like crazy but ive sprayed either around everything on the intake and throttle body to see if it raised up the rpm any and nothing. Ive checked the vaccum tee and it seems to be fine. Its got me puzzeld. I know my way around mechanicing and ive checked everything that i could check as far as vaccum goes in the engine bay. Ive even pulled out my stereo and half my dash to check in the dash to see what i could find. But as far as power loss goes im not throwing any codes, all of the exaust is brand new from the y pipe back... Just had a new converter and a single in dual out flowmaster put on with 3 1/2" tail pipes put on. The only thing is if i have it in park and rev the motor its fine but as soon as i put it in gear and mash on it thats when all the problems start. I literaly have to keep it out of overdrive cause it wont pull a lil hill if i dont. Stock 3.55 gears and im only running 33's on the truck. It shouldnt have killed it that bad.

 

Have you checked the plenum? An external inspection will reveal nothing. You actually have to pull the throttle body and look.

How many miles on the truck?

Did you replace the O2 sensors when you did the exhaust?

 

i havnt pulled the throttle body yet... Ive got roughly 139,000 miles... And no i didnt replace the o2 because it hasnt showed a code for anything...

 

Are you getting lots of blow-bye in the crank. Mabye you have a problem with a valve. I would suggest taking right back to the basics. Check the compression, and if it's good do a leak down test. This test is a more accurate test. You can have good compresion but still have a bad valve or a craked head or something wrong with the rotating mass. If that is all good check the timming.
I also can't remember if you can program the TCM for the bigger tires. If not I would suggust you bring it to a tranny shop and have them tighten up the TV cable so that it can compensate for the bigger tires.

On another note my friend has the same truck as you. He has owned since new and it has always been a dog. When he put his 31 inch tires on it was even worse. It would gear down up the smallest of hills and thats just the way it was. Is this truck new to you? If not when did you notice the power loss. ie (modifications etc)

Good luck

 

There is a vac line that runs under the battery compartment. Due to corrosive gases from the battery, it tends to go first. There's also a vac canister under there you might double check.

Also, check the end of the hose on the evap return line that goes to the front of the throttle body for cracks, as well as the tiny elbow under the MAP sensor if you are hearing whistling around the TB.