97 PA 3.8L 155,000mi missing/slipping?

Hi Everyone,
I've just noticed an odd "feel" to my Park Avenue when driving. I've never had any vehicle with transmission issues, so I don't know what that feels like. Here's what's happening...Car starts fine, heading for work at about 40mph, I notice a few bumps/hiccups, then when I got to a stop light, put it in neutral and still felt an occasional bump/hiccup type feeling from the car. Thought it might be something transmission related, but when I put the car in neutral, it still did it. I've driven it a couple days like this and it happens in cool and normal running conditions. I've read a bunch of information on problem transmissions, so I put some Lucas trans. fix in, as per instructions, but no fix.
Maybe it's not the transmission at all? No codes are showing on the OBD system.
Had the Trans serviced about 15,000 miles ago, with high mileage fluid and new filter. Also had crank shaft and cam shaft sensors replaced, as I had a code for the one and decided to go ahead and replace both.
I do get a jolt sometimes, I feel it going into overdrive, but not always. This has been going on since before I had the trans. serviced. The fluid change and sensor changes didn't seem to help this issue.
Any ideas where I might look for the solution to the problem(s)?
Thank you,
Wendy:uhoh:

Change the fluid and filter again to get rid of all the junk released by the fluid change 15,000 miles ago.

This jolt can be internal or a possible bad trans/engine mount, it should be driven/tested on site by an experienced tech.

When was the last time you changed plugs & wires? In addition, if they were recently changed, what plugs & wires were installed. BTW, if this "bump/hiccup" takes place with the trans in neutral at a stop, it is not trans related.

Agree, bad wires could cause the problem you describe.

Just had the SES light come on, guess it got bad enough. So I checked w/the code reader and it gave me a P0301 code, misfire cyl 1. I had work done about 2 months ago on the bad intake gasket, so maybe one of the wires is really loose. I'll check wires and plugs, but it may be time to replace all.
Thank you for your ideas and help. Now I know what a bad misfire feels like! Ha Ha!
Wendy:lol2:

Check the terminals of the coils....may find corrosion/arcing marks....

If the wires still have the cylinder #'s on them, you are long overdue for wires...

Thank you for all of your suggestions concerning the problem I posted. Found out it was a bad spark plug wire. The last mechanic to work on my vehicle pulled too hard on the plug wire and simply pulled it off the metal connector.
I did buy a new set of wires, as the ones on the car are probably original. Might as well replace them all.
I was able to push the wire back into the boot and get it close enough to the plug that when I drove to the auto parts store, there were no misfires or bucking. Funny how that just happened.
Guess I still don't know what a "slipping" transmission feels like. Ha Ha.
Thanks again,
Wendy:biggrin: