Camry engine misfires

Faulty spark plugs, Faulty leads, coil breaking down, fuel pressure problems, blocked air filter, i would be looking at electrical first.

We had our engine replaced at almost 111,000 miles (failure to hold oil pressure) with one that had about 59,000 miles. We were away from home, so the shop that did the work did not do an adequate job. The valve cover and spark plug tubes were not properly sealed. The spark plug wires were arcing. Our mechanic fixed these issues and it drives fine, but when it hits the 4200 rpm mark, that is when it misfires. It will not go past that point.

The crank shaft sensor is fine.

The timing belt is is not the issue.

They do not know the exact year of the engine, but it is matched based on the vehicle VIN when the part is sourced. The manager said it was probably the 2.2L engine and within a year or two of 1999.

The engine meets federal emissions standards, not California (as would be expected).

They used the existing wiring harness from our car as it is part of the engine block.

In talking to the mechanic on Friday, he mentioned that the MAF sensor was reading 5-6 Volts? mV? (whatever the units are, but he said it was voltage) high. So the vacuum in the engine at this level rpm (4200) is too high.

One of the problems is testing it at this rpm level since it is accelerating at highway speeds that causes it. Another problem is that there are no error codes.

The plugs used were not iridium, but platinum when the new engine was put into the car.

Check for vacuum leaks. Check the coils and pickups/sensors. Run some fuel system cleaner through the tank to make sure there is no varnish built up on the tips of the injectors or the valves. USe a fuel pressure gauge to check fuel delivery pressure throughout the RPM range.