[SVXRide]

Originally Posted by lee

Last Friday filled up (w/93 octane) at a Chevron station where I frequently buy my gasoline. Drove home (about 8 miles) and parked the car overnight. Didn't drive it again until Sunday morning to make the run for the newspaper. Car stumbled/shuddered pretty bad. Thought maybe I got a load of bad gas, so since then I have put in a bottle of Techron and 2 qts of toluene. Running better but not right. Here's what it's like today....

Once up to speed, and on flat ground (like there's any other kind around here), the car runs fine, don't feel any engine misfires. When at about 1/3 to 2/3 throttle there is some stumbling. When at WOT, there is sometimes a surging sensation - where it changes from full-strength acceleration to something less- still relatively smooth, but down on power.

Does this during "first run of the morning" cold to fully warmed up - but cold is a bit worse.

Just filled up on my way home today with Shell V-Power. Only drove about a mile to the house, and it's parked until I go to work tomorrow.

Interestingly, I normally get about 19.8 mpg. I drive a pretty standard route to/from work up & down Hiway A1A. The mpg for this tank while suffering the performance issue - 24.2 mpg!? It wasn't babied either, I accelerated harder than normal to avoid running in the middle throttle position and getting all that misfire.

No check engine light, no hard starting. Haven't yet checked anything except battery ground.

So,

Lee,
given that when you put in the techron and toluene it ran better and you're experiencing surging, I'd take a look at the injectors and/or the fuel filter.
-Bill