94 Park Avenue missing

First off, I just found this place and it is very cool.

I have a 94 PA (140,000 miles) that seems to be missing when under a slight load (i.e., going up a slight grade or pressing on the accelerator very lightly). The car vibrates and there is a sizzling noise coming from under the hood. When it happens the rpm's jump up 100 or so, when it stops the rpm's drop back down. Seems to happen more when the car has been run for approximately 20 minutes.

In the beginning I thought it was a transmission issue so I took it in and had the shop do a BG flush and fill. Seemed to help the problem a little, but it came back.

Then I noticed the sizzling noise under the hood so I replaced the plugs and checked the plug wires for leaks. No leaks. I have also checked the vacuum on the motor (it's fine), cleaned the MAF, cleaned the fuel injectors and ran Sea Foam through the tank.... The problem is still there. I have searched the forum, but have not really found a problem exactly like this with fixes I haven't tried. Anyone have an idea what it could be?

Thanks.

Did you remove the plug wires check the terminals for corrosion & check the wires for resistance? Checking the wires for "leaks" is not a very effective diagnostic tool! Be sure to check all wire terminals on the coils & plugs and look for anything that appears different than the others.

I was being a little facetious with the "checking for leaks," I have inspected the other components and nothing seems out of the ordinary. There are no rough/burned/corroded..... areas, but I installed wires just in case. I also bought a single coil and rotated it through each position and still had the problem no matter where the new coil was. I suppose the new coil could be bad, or 2 of the old ones could be. Is it worth it to buy 2 more coils (about $50-60 total) or am I barking up the wrong tree?

Check the vacuum hoses, especially the molded U-shaped ones right on top of the plenum.

From your description it does sound like an intermittant vacuum leak,also check the vacuum canister for bad hoses,good luck and please post you findings.

Checked the cannister and all "seems" to be in order. The hoses are in what appears to be good shape. Re-checked for other vacuum leaks at idle with a can of starting fluid.

Took it back in to the shop the other day and they drove it with the diagnostic equipment hooked up. Came back with a Torque Converter code. I'm not buying it. Perhaps an electrical problem is causing the TC to show a code?

i put one on the machine and it ran fine but after unhooking it went back to the missing said a ground wire was braking down. so i ended up putting a module under coil pack and cured it. my check engine light was on but it had been for a long time so i put a new tps sensor on it and that cured that to.