So what do you think is wrong?

[rocky]

It began subtly. Almost a misfire. Then I started to notice a hesitation when accelerating. At first perhaps when cornering but also in a straight line. Also had two pops from under the floorboards which I suspect is fuel getting burnt in the cats.
The hesitation on accelerating has gotten worse during the day. Hopefully it will keep going until I get home. I also think it's worse after the two or three miles from a start hot or ccold.

Of course I go out of town for a couple of weeks on Tuesday. So maybe tomorrow will be my only chance to dig in.

 

[chuckc4]

Did you notice any odd tapping noises?

Can you check to see if you are getting a misfire code?

Purely speculative, could the exhaust pop indicate you have a sticking or burnt valve

 

[RBBailey]

Check the usual stuff. Look for dirt where it ought not be. Look for vacuum breaks. Broken leads, wires, and dirty plugs. Clean the intake with Sea Foam (don't hit the MAF!). Look at the O2 sensors, and at any possible rattle/cracks in the exhaust. And check for codes.

 

[sherpamike]

Sounds like a misfire I was dealing with last week. I was losing power on acceleration and could hear and feel the misfire. When I got home I let it idle in the garage and popped the hood. I could see arcing from one of the plug wires to the valve cover. Went out of town this weekend so haven't had a chance to mess with it yet but I have new wires and will check the plugs too. Probably should check the timing while I'm at it.

Just my $0.02

 

[rocky]

I'm a fan of working through the cheaper items first. I've got some plug wires and plugs coming while I'm away the rest if the week in Maine. Next weekend is filling up fast!

 

[jymmiejamz]

What engine/engine management is it?

I would recommend not throwing parts at it as you can inadvertently create a new similar symptom.

 

[rocky]

Its a 3.9 D1 Serp from a 95 MY. I'm OCD when it comes to plugs and wires. I replace one at a time then restart to simplify fault finding in the event that a problem arises.

 

[jymmiejamz]

Do you have any way of looking at the live data? I think there are some cheap options for this, but I'm not certain.

 

[rocky]

Moments like this I wish it was obd2 so you can monitor data in real time.

 

[Uncle Douglas]

My .02, I'd start with a compression check. Fast, easy, and free. Since plugs are $2 ea I put new ones in when I test compression, saves going back and doing it.

 

[rocky]

My .02, I'd start with a compression check. Fast, easy, and free. Since plugs are $2 ea I put new ones in when I test compression, saves going back and doing it.

A CT was in my mind as a smart thing to do...... Thanks for confirming the thought. Going to be interesting to see if the plugs tell a tale....

 

[rocky]

Wanted to follow up on this. I haven't covered many miles since Memorial Day weekend. Much of my time I've been working in Maine.
The few trips I've taken since this happened. it's been fine. Currently, my #1 suspect is the tank of gas I got just before this all started. I refilled early and it hasn't happened again.
Of course I've jinxed myself now.
This weekend will see another 100 miles or so. If it comes back, I'll know about it.