'93 Impreza 1.8 engine miss/hicup

I just purchased this car about 2 month ago and it stutters between ~1700-2500rpm. Sometimes it's hardly noticable, other times it will jerk the car, not violently but you can feel it definitely. It doesn't seem temp related. If I get past 3000, it pulls smooth to red line. On the low end it doesn't stutter either. It idles like a sewing machine..super smooth. It is most noticable in 2nd and 3rd when the engine is under load. There is no CEL on and car has 165k on it.

I have replaced the following:

- plugs

- wires

- PCV valve

- fuel and air filter

- crank and cam position sensors

I have checked or done the following:

- 1 bottle of techron (1st tankfull)

- 1 can of seafoam (half into the intake, half in the gas tank, 2nd tankfull)

- 2 bottles of heat (3rd tankfull)

- Grounding kit, re-tourqed stock ground points

- Resistance on fuel injectors is 11.4 ohm accross the coils on all 4

- EGR tested good, bogged engine when vacuum present

- coil has no sign of deposits or corrosion...not saying it's not bad but....

I don't know how to pull OBDI codes or I would have done that. I did a lot of searches on this board and others and found a lot of suggestions for similar problems but no definitive answers. Sometimes folks don't post back though when they do have a solution The fuel economy is great, 28mpg avg. in three tank fulls and I'm not on the highway much.

Obviously I feel like I'm down to all the expensive stuff. Coil, MAF, TPS or injectors. Sorry for the long post but I didn't wanna keep saying "I tried that". Thanks in advance for any input!

Brent