caprice classic chugging when accelerating

[3652duke]

1994 Chevy caprice classic chugging when accelerating between 25 mph - 60 mph and when passing (at more than 3/4 throttle.) Fuel filter? Fixed a vacuum leak but that didn't do it. Plugs and fuel filter is next.

Just wanted to know if there are any other common causes I should look for.

[jdl]

I'd put a fuel pressure gage on it and check applicable trouble codes.

[Blue Bowtie]

If the plugs are due for replacement, that would be a good step. If that doesn't solve the issue and fuel pressure is correct, the Opti may need diagnosis. A distributor cap breaking down internally can start to exhibit symptoms like this (spark blowout under load) before it completely fails.

If the car has more than 100K on the odometer and the Opti has not been serviced, it may be a possibility. Since the engine presumably runs normally otherwise, the optics are probably O.K. and the cap/rotor may be failing.