I'm not sure if this is a problem or not. My car ('87 n/a) feels faster/peppier after I gas up and then seems to bog more and more as the days go by. I fill up $20 of 87 octane from Sunoco about every 4 days of driving. My car has an idling issue and a bit of the 3000 hesitation. I only noticed the difference during the last 2-3 times that I've gassed up. Any suggestions on what could be the problem here?

 

Hmmm. $20 probably only gives you like a 1/4 tank. That's not much gas, you might be sloshing fuel around as it gets lower and could be missing fuel at times. I was always told to keep a fuller tank of gas, makes sure that the pump is always well supplied with fuel even around hard turns.
That's why people build surge tanks and custom fuel cells, as the fuel level drops it becomes harder to keep the pump supplied during spirited driving, if you are not pulling enough fuel you could lean out and pop the motor.

Try keeping the tank higher and see if that helps.

 

Just as a guess: the tank could be dirty. A lot of people run into problems after running it empty, and some people get problems after running it near empty several times.

The owner's manual "strongly recommends" that you clean out the fuel tank annually. It also recommends a mechanic do this due to the dangers of working around gasoline & gasoline vapors (i.e., boom). I asked a mechanic about this and he said it was unnecessary, but after 20 years I'm thinking it should be done at least once. I hear from people who do it their self and their tank is always super gunked up. Search forums for more info.

In the mean time try filling up all the way to full and use good detergent gas (Chevron/Texaco/76/Shell). If you want an additve try Techron concentrate but even good additives aren't the same as actually getting your hands dirty and dealing with the fuel tank/fuel sock/fuel filter/fuel injectors, nor are they ever necessary if you do things the right way.

Or it could be in your imagination. Or if you're having trouble around turns it could be rusted out fuel baffles. But I assume you'd find rusted baffles from looking in the fuel tank anyway.

 

@ NJGreenBudd - At current gas prices ($2.35), $20 surprisingly gets me about 1/2 tank of gas and I always fill up around 1/8 of a tank. I'll try keeping the gas tank higher and see how that goes.

@ ericgrau - I'll definitely look into cleaning the tank as I don't think it's ever been done before and I'll check out the fuel baffles as well. I seem to only notice the difference while driving straight and not during turns.

Thanks guys. ^_^

 

Just be careful cleaning the tank, it's easy to make it worse initially by loosening all of the sediments and debris on the tank bottom. If you start the process you have to really follow through and get the whole thing clean so there aren't particles floating around.

Start with keeping the tank higher and see if you notice anything. Couldn't hurt to do a fuel filter replacement though if it hasn't been done lately, you could also clean the sock filter on the pump - that would give you a good idea of what shape your tank is in. Just be careful messing around with the gas tank and fuel stuff, plenty of harmful vapors and one big fire hazard.