Watery Beer

I recently moved from extract to all grain brewing and have been experiencing problems with beer that has a hollow or watery taste after fermentation. All my number look right throughout the entire process however the finished product lacks the flavor characteristics I am looking for. I have been using a single step infusion mash at approximately 154 F for 60 to 90 min and using iodine to test for complete conversion. After boil my OG is right on and after fermentation my FG is always close. Has anyone else had a problem like this?

i have been having the same problem - depending on the style i have taken to
adding extra crystal .
my last ale i also mashed at 156-157 and noticed better mouthfeel and aftertaste

Maintaining mash temperature is the toughest part of all grain. Since it is easy for temperatures to drop a little on the edges of the tun, mashing at 154F can result in thinner, more fermentable worts. Slightly higher temperatures will reduce the beta amylase activity and give you better mouthfeel and more body. Your attenuation will be slightly lower.

Are you sure your thermometer is reading true?

Could be that you are actually mashing at a lower temperture than what you want.

How much are you sparging? and what is your final wort volume?

I've had the same experience recently. I switched from extract to all grain, and mashed at lower temperatures to get a higher alc content. But some of my beers, especially the lighter ones just don't have any pizazz! Watery.

I've decided to up my mash temp a few degrees to give me more body. That's what I really like in beer.

david brings up a good point about the edges cooling faster than the center. What kind of MT do you use (cooler/keg/bucket)? Do you stir and let rest for a few min before taking the temp reading? A few degrees has a big effect on the final beer.

Although it is no substitute for improper mashing, you could always adjust body by adding specialty grains, etc. Using some crystal or some malto-dextrin will increase mouthfeel and body. Additionally, don't rely upon the tasting of your uncarbonated beer at bottling time. Carbonation will add a certain degree of mouthfeel and perception of body - so, a beer that is watery at bottling time may be perfect when you drink it.